feat(rdn2): enable AMU if present on the platform

Set build-option ENABLE_FEAT_AMU to 2 so that AMU is enabled if the
feature is implemented on the platform. This would ensure that lower ELs
could access system registers relevant to AMU without causing a trap to
EL3.

Signed-off-by: Rohit Mathew <rohit.mathew@arm.com>
Change-Id: Ic9aa435af54eddacdaa49e69f25893ddaa977e3e

plat/arm/board/neoverse_rd/platform/rdn2/platform.mk

@@ -104,7 +104,7 @@ $(eval $(call TOOL_ADD_PAYLOAD,${TOS_FW_CONFIG},--tos-fw-config,${TOS_FW_CONFIG}
 endif
 
 override CTX_INCLUDE_AARCH32_REGS	:= 0
-override ENABLE_FEAT_AMU		:= 1
+override ENABLE_FEAT_AMU		:= 2
 override ENABLE_FEAT_MTE2       	:= 2
 
 # Enable the flag since RD-N2 has a system level cache