arm/arm64: KVM: Report correct FSC for unsupported fault types

arm/arm64: KVM: Report correct FSC for unsupported fault types

When we catch something that's not a permission fault or a translation
fault, we log the unsupported FSC in the kernel log, but we were masking
off the bottom bits of the FSC which was not very helpful.

Also correctly report the FSC for data and instruction faults rather
than telling people it was a DFCS, which doesn't exist in the ARM ARM.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
(cherry picked from commit 0496daa5cf99741ce8db82686b4c7446a37feabb)
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>