Pull Xen fixes from Stefano Stabellini:
 "A small fix for Xen on x86_32 and a build fix for xen-tpmfront on
  arm64"

* tag 'stable/for-linus-3.12-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen: Fix possible user space selector corruption
  tpm: xen-tpmfront: fix missing declaration of xen_domain