[PATCH] MSI-X: fix resume crash

So I think the right solution is to simply make pci_enable_device just
flip enable bits and move the rest of the work someplace else.

However a thorough cleanup is a little extreme for this point in the
release cycle, so I think a quick hack that makes the code not stomp the
irq when msi irq's are enabled should be the first fix.  Then we can
later make the code not change the irqs at all.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>