arch-arm: CNTHCTL trap to EL2 only if ARMv8.6-ECV implemented

arch-arm: CNTHCTL trap to EL2 only if ARMv8.6-ECV implemented

In condGenericTimerCommonEL1SystemAccessTrapEL2 we were trapping
accesses to the EL1 virtual timer/counter registers to EL2, not
considering that this feature is part of ARMv8.6-ECV only
(not supported at the moment)

Change-Id: Ic03bcae436a105fb139a74126881b665ee08c912
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Adrian Herrera <adrian.herrera@arm.com>
Reviewed-by: Richard Cooper <richard.cooper@arm.com>
Reviewed-by: Ciro Santilli <ciro.santilli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/27408
Tested-by: Gem5 Cloud Project GCB service account <345032938727@cloudbuild.gserviceaccount.com>
Tested-by: kokoro <noreply+kokoro@google.com>