feat(neoverse-rd): add SRAM layout for third gen platforms

Given the differences in memory map and additional RME requirements for
the V3 CPU based platforms, it is necessary to move away from the common
SRAM layout present as part of arm_def.h. Therefore, introduce
definitions and necessary carveouts within SRAM to define a new SRAM
layout for these platforms.

Signed-off-by: Rohit Mathew <rohit.mathew@arm.com>
Change-Id: I2d0ef65abde66da7523dd9e09036c7803978570c
3 files changed