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 <arunachalam.ganapathy@arm.com>
Change-Id: I7d930d96ec22d7c3db961411370564bece0ce272

plat/arm/board/tc0/platform.mk

@@ -114,6 +114,8 @@ override CTX_INCLUDE_PAUTH_REGS	:= 1
 
 override ENABLE_SPE_FOR_LOWER_ELS	:= 0
 
+override ENABLE_AMU := 1
+
 include plat/arm/common/arm_common.mk
 include plat/arm/css/common/css_common.mk
 include plat/arm/soc/common/soc_css.mk