yocto/trusted-firmware-a: Move BL31 to SRAM

BL31 in TF-A contains runtime services to other firmware and Linux. The
RD-N2-Automotive stack is currently based on RD-INFRA-2022.08.18, where
BL31 lives in an area of DRAM reserved for the secure world.

To further isolate BL31 from the normal world software, backport 2
patches from TF-A 2.8 which move BL31 to SRAM. The first patch increases
the SRAM image size to account for BL31 and the second changes the
default value of ARM_BL31_IN_DRAM to 0.

Issue-Id: SCM-5314
Signed-off-by: Peter Hoyes <Peter.Hoyes@arm.com>
Change-Id: I1777e728d3325673b68a2a940c9c588332259818