To accommodate the increasing size of the SCP_BL2 binary, the base
address of the memory region allocated to SCP_BL2 has been moved
downwards from its current (mostly) arbitrary address to the beginning
of the non-shared trusted SRAM.

Change-Id: I086a3765bf3ea88f45525223d765dc0dbad6b434
Signed-off-by: Chris Kay <chris.kay@arm.com>