* changes:
feat(cpufeat): constrain RAS_TRAP_NS_ERR_REC_ACCESS on ENABLE_FEAT_RAS
fix(build): set defaults to feature flags before platform.mk
refactor(cpufeat): unify FEAT_IDTE3's definitions with arch.h
refactor(el3-runtime): generalise sysreg trapping
refactor(el3-runtime): use contexted SCR_EL3 instead of the register
build: rename default_ones to set_ones