Pull xen bug fixes from David Vrabel:
 - Fix arm64 crash on boot.
 - Quiet a noisy arm build warning (virt_to_pfn() redefined).

* tag 'stable/for-linus-3.15-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  arm64: introduce virt_to_pfn
  xen/events/fifo: correctly align bitops
  arm/xen: Remove definiition of virt_to_pfn in asm/xen/page.h