arch-arm: Add System register trap check for EL1

arch-arm: Add System register trap check for EL1

This change adds and refactors the register trap checks
for EL1 in the same function, unifying the registry trapping

Change-Id: Ief3e0a9f70cc8cd44c1c8215515f36168927362d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/31694
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>