fix(rdv3): remove NEED_* from RD-V3 makefile

As the NEED_* are internal flags used in the build system and are not
meant to be used by platforms, remove them from the RD-V3 makefile.

Signed-off-by: Jaylyn Ren <Jaylyn.Ren2@arm.com>
Change-Id: If7144b9d72c16e8025f929f2546abd96194615ce