KVM: arm64: Replace fault_is_perm with a helper

KVM: arm64: Replace fault_is_perm with a helper

Carrying a boolean to indicate that a given fault is a permission fault
is slightly odd, as this is a property of the fault itself, and we'd
better avoid duplicating state.

For this purpose, introduce a kvm_s2_fault_is_perm() predicate that
can take a fault descriptor as a parameter. fault_is_perm is therefore
dropped from kvm_s2_fault.

Tested-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>