plat/arm: Compile out impossible conditional for AArch32
plat/arm: Compile out impossible conditional for AArch32

Since ARM_DRAM2_BASE is above the 32-bit limit, the condition
is always false.  Wrap this condition in an ifndef to avoid
warnings during compilation.

Change-Id: Ideabb6c65de6c62474ed03eb29df4b049d5316be
Signed-off-by: dp-arm <5172875e934a989df22d22726b6d9d921b91fbdd@arm.com>

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware,lsigithub/arm-trusted-firmware_public,lsigithub/arm-trusted-firmware_public