refactor(neoverse_rd): refactor header files for second gen platforms

TF-A underwent a major rehaul in directory structure. This change
deals with refactoring the header files for second generation platforms
grouped as nrd2 in TFTF to a structure that aligns with that of TF-A.

Change-Id: I263a91e768644b491a0dc2b706e7c88d6b65e8a9
Signed-off-by: Jerry Wang <Jerry.Wang4@arm.com>
4 files changed