docs(build-options): add build macros for features FGT,AMUv1 and ECV

This patch adds macros explicit to the features - FEAT_FGT,FEAT_AMUv1
and FEAT_ECV respectively. It assists in controlled access to the set
of registers (HDFGRTR_EL2, HAFGRTR_EL2 and CNTPOFF_EL2) under the
influence of these features during context save and restore routines.

Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Change-Id: I5082ea6687a686d8c5af3fe8bf769957cf3078b0
1 file changed