ppc/spapr: Fix FWNMI machine check interrupt delivery

FWNMI machine check delivery misses a few things that will make it fail
with TCG at least (which we would like to allow in future to improve
testing).

It's not nice to scatter interrupt delivery logic around the tree, so
move it to excp_helper.c and share code where possible.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Message-Id: <20200316142613.121089-5-npiggin@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
3 files changed