Pull Xen build fix from David Vrabel:
"Fix arm build of drivers/xen/events/
The merge of irq-core-for-linus branch broke it"
* tag 'stable/for-linus-3.15-tag2' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
Xen: do hv callback accounting only on x86