target/ppc: Fix facility interrupt checks for VSX

target/ppc: Fix facility interrupt checks for VSX

Facility interrupt checks in general should come after the ISA version
check, because the facility interrupt and facility type themselves are
ISA dependent and should not appear on CPUs where the instruction does
not exist at all.

This resolves a QEMU crash booting NetBSD/macppc due to

  qemu: fatal: Raised an exception without defined vector 94

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2741
Cc: Chinmay Rath <rathc@linux.ibm.com>
Cc: qemu-stable@nongnu.org
Debugged-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Fixes: aa0f34ec3fc7 ("target/ppc: implement vrlq")
Fixes: 7419dc5b2b5b ("target/ppc: Move VSX vector storage access insns to decodetree.")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>