Improvements to ARM GIC driver

This patch introduces several improvements to the ARM GIC driver:

* In function gicd_set_itargetsr(), target CPU is specified using
  the same bit mask detailed in the GICD_ITARGETSRn register instead
  of the CPU linear ID, removing the dependency between bit position
  and linear ID in the platform porting. The current CPU bit mask
  may be obtained by reading GICD_ITARGETSR0.

* PPIs and SGIs are initialized in arm_gic_pcpu_distif_setup().
  SPIs are initialized in arm_gic_distif_setup().

* By default, non secure interrupts are assigned the maximum
  priority allowed to a non secure interrupt (defined by
  GIC_HIGHEST_NS_PRIORITY).

* GICR base address is allowed to be NULL for GICv1 and GICv2.

Change-Id: Ie2837fe860d43b2282e582dfdb13c39c6186f232
Juno: Use the generic ARM GIC driver

This patch replaces the usage of the GIC private driver in Juno with
the generic ARM GIC driver. The private driver is no longer necessary
and has been removed from the Juno port.

Fixes ARM-software/tf-issues#253

Change-Id: I6aaabc252e5e6fb5fcf44ab6d0febd9b38791056
Merge pull request #219 from jcastillo-arm/jc/tf-issues/253

Improvements to ARM GIC driver
Juno: Use the generic ARM GIC driver
Use the BL3-1 runtime console as the crash console.

This patch reassigns the crash console on Juno and FVP to use the runtime
BL3-1 console. The crash console is changed to SoC UART0 (UART2) from the
previous FPGA UART0 (UART0) on Juno. In FVP, it is changed from UART0 to
UART1.

Fixes ARM-software/tf-issues#256

Change-Id: I7df54f86ca00ec2652c27261dd66a94c12610816
Precede a 'sev' with a 'dsb' in bakery lock code

This patch fixes a bug in the bakery lock implementation where a data
synchronisation barrier instruction is not issued before sending an event as
mandated by the ARMv8 ARM. This can cause a event to be signalled before the
related memory accesses have completed resulting in erroneous execution.

Fixes ARM-software/tf-issues#272

Change-Id: I5ce02bf70afb001d967b9fa4c3f77442931d5349
Merge pull request #221 from achingupta/ag/tf-issues#272

Precede a 'sev' with a 'dsb' in bakery lock code
Merge pull request #220 from soby-mathew/sm/reassign_crash_console

Use the BL3-1 runtime console as the crash console.