arch-arm: Handle route to EL2 in Supervisor Trap

arch-arm: Handle route to EL2 in Supervisor Trap

Supervisor Trap is supposed to be able to handle exceptions routed
to EL2, which is enabled by HCR_EL2.TGE. This fix adds routeToHyp()
function to Supervisor Trap to handle this, similar to that in
UndefinedFault, DataAbort, etc.

Change-Id: I1fcf9f2d445ecbc13c8f6d3b7d599728b0250ab7
Reviewed-by: Jack Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/7961
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>