xen: don't call dpm_resume_noirq() with interrupts disabled.

dpm_resume_noirq() takes a mutex, so it can't be called from a no-interrupt
context.  Don't call it from within the stop-machine function, but just
afterwards, since we're resuming anyway, regardless of what happened.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stable Kernel <stable@kernel.org>