arch-arm: Adapting IllegalExecution fault for AArch32

arch-arm: Adapting IllegalExecution fault for AArch32

The Illegal Execution fault triggered by the setting of processor state
PSTATE.IL happens in AArch32 as well and takes the form of UNDEFINED
exception fault.  We are hence copying the UndefinedInstruction AArch32
fields into the IllegalInstSetStateFault.

Change-Id: Ibb7424397c2030ea5d010577c530277a27036aea
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10814
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>