UPSTREAM: KVM: arm64: Move pkvm's special 32bit handling into a generic infrastructure

Protected KVM is trying to turn AArch32 exceptions into an illegal
exception entry. Unfortunately, it does that in a way that is a bit
abrupt, and too early for PSTATE to be available.

Instead, move it to the fixup code, which is a more reasonable place
for it. This will also be useful for the NV code.

Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
(cherry picked from commit 7183b2b5)
Bug: 204960018
Signed-off-by: Will Deacon <willdeacon@google.com>
Change-Id: I9e8926e8c9cd9399073216abb8885a3e2613836f