Extend SPSR definitions for full use of ELx modes

Extended SPSR definitions with all the fields to allow full use
of EL2/EL1 execution modes for entry points
Replaced make_spsr() with SPSR_64 macro and added SPSR_32 macro
for generating AARCH32 mode SPSR

Change-Id: I9425dda0923e8d5f03d03ddb8fa0e28392c4c61e
Rework handover interface between BL stages

This patch reworks the handover interface from: BL1 to BL2 and
BL2 to BL3-1. It removes the raise_el(), change_el(), drop_el()
and run_image() functions as they catered for code paths that were
never exercised.
BL1 calls bl1_run_bl2() to jump into BL2 instead of doing the same
by calling run_image(). Similarly, BL2 issues the SMC to transfer
execution to BL3-1 through BL1 directly. Only x0 and x1 are used
to pass arguments to BL31. These arguments and parameters for
running BL3-1 are passed through a reference to a
'el_change_info_t' structure. They were being passed value in
general purpose registers earlier.

Change-Id: Id4fd019a19a9595de063766d4a66295a2c9307e1
Populate BL31 input parameters as per new spec

This patch is based on spec published at
https://github.com/ARM-software/tf-issues/issues/133

It rearranges the bl31_args struct into
bl31_params and bl31_plat_params which provide the
information needed for Trusted firmware and platform
specific data via x0 and x1

On the FVP platform BL3-1 params and BL3-1 plat params
and its constituents are stored at the start of TZDRAM.

The information about memory availability and size for
BL3-1, BL3-2 and BL3-3 is moved into platform specific data.

Change-Id: I8b32057a3d0dd3968ea26c2541a0714177820da9
Rework memory information passing to BL3-x images

The issues addressed in this patch are:

1. Remove meminfo_t from the common interfaces in BL3-x,
expecting that platform code will find a suitable mechanism
to determine the memory extents in these images and provide
it to the BL3-x images.

2. Remove meminfo_t and bl31_plat_params_t from all FVP BL3-x
code as the images use link-time information to determine
memory extents.

meminfo_t is still used by common interface in BL1/BL2 for
loading images

Change-Id: I4e825ebf6f515b59d84dc2bdddf6edbf15e2d60f
Add support for BL3-1 as a reset vector

This change adds optional reset vector support to BL3-1
which means BL3-1 entry point can detect cold/warm boot,
initialise primary cpu, set up cci and mail box.

When using BL3-1 as a reset vector it is assumed that
the BL3-1 platform code can determine the location of
the BL3-2 images, or load them as there are no parameters
that can be passed to BL3-1 at reset.

It also fixes the incorrect initialisation of mailbox
registers on the FVP platform

This feature can be enabled by building the code with
make variable RESET_TO_BL31 set as 1

Fixes ARM-software/TF-issues#133
Fixes ARM-software/TF-issues#20

Change-Id: I4e23939b1c518614b899f549f1e8d412538ee570
Allow BL3-2 platform definitions to be optional

The generic image loading and IO FIP code no longer forces the
platform to create BL3-2 (Secure-EL1 Payload) specific
definitions. The BL3-2 loading code in bl2/bl2main.c is wrapped
by a #ifdef BL32_BASE blocks, allowing the BL3-2 definitions to
be optional. Similarly for the name_uuid array defintion in
drivers/io/io_fip.c.

Also update the porting guide to reflect this change.

The BL3-2 platform definitions remain non-configurably present
in the FVP port.

Fixes ARM-software/tf-issues#68

Change-Id: Iea28b4e94d87a31f5522f271e290919a8a955460