fix(plat/tc0): enable AMU extension
fix(plat/tc0): enable AMU extension

Recent changes to enable SVE for the secure world have disabled AMU
extension by default in the reset value of CPTR_EL3 register. So the
platform has to enable this extension explicitly.

Signed-off-by: Arunachalam Ganapathy <dce9338f710b9095e42fdce770812a0fef195629@arm.com>
Change-Id: I7d930d96ec22d7c3db961411370564bece0ce272

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware