arch-arm: ELUsingAArch32K from armarm pseudocode

arch-arm: ELUsingAArch32K from armarm pseudocode

This patch implements the ELUsingAArch32K pseudocode, which is returning
true if the provided Exception Level is using A32 ISA, but it is not
panicking (quitting simulation) if the information is unknown (see
documentation).
The panicking is the current behaviour of the ELIs32 utility in gem5.

Change-Id: Iad7b56077d7e0f8ee223b5b9593cb8097f26bb29
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/7222
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>