Cleanup loading/unloading of a TA

* A TA is only loaded via tee-supplicant, directly supplying a
  pointer to the TA binary is not supported any longer.
  This requires and update to the client lib to avoid leaking
  shared memory.
* The shared memory used to load the TA is freed as soon as the
  TA have been loaded into secure memory
* Divides tee_ta_init_session() into sevaral functions
* Divides tee_ta_close_session() into two functions
* Divides tee_ta_load() into several functions with one
  separate function for signature verification
* Removes some unused code for kernel TAs
* Removes the option to lock/unlock a TA is only used by kernel
  TAs which we don't support any longer.
* Removes the static global tee_rs. Switch to use Thread Local
  Storage pointer provided by the thread handler.
* Adds TA_FLAG_USER_MODE by default to TA header since
  all TAs are user mode TAs now.
* Reformats user_ta_header.c to make checkpatch less unhappy with it.
mk/compile.mk: simplify dependency generation; better support ccache

This commit modifies the compilation flags that are used to generate
dependency files (*.o.d). Rather than using the preprocessor's -MD flag
(-Wp,-MD,<depfile>), we now use the frontend's equivalent (-MD -MF <depfile>
-MT <target>).

There are three reasons for doing so:
  1. The GCC man page recommends against using -Wp, because "the
preprocessor's direct interface is undocumented and subject to change".
  2. The new flags generate the correct rule directly, including the
subdirectory in front of the object name, so scripts/fixdep is not needed
anymore.
  3. ccache (3.1.9) would not handle -Wp,-MD as expected. It would preserve
the directory prefix, so that we would end up with an invalid path after
the fixdep phase, making the rules useless. With this patch, OP-TEE builds
fine with ccache:
     make -j3 CROSS_COMPILE="ccache arm-linux-gnueabihf-"
Add GIC status dump utility

- fixed fvp gic cpu interface and distrubtor offset
- added new mapping for distrubtor
- add utility to dump gic status
Add a flag to turn on/off PSCI debug msg