Pull xen updates from Juergen Gross:

 - a small series to remove the build constraint of Xen x86 MCE handling
   to 64-bit only

 - a bunch of minor cleanups

* tag 'for-linus-5.5a-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen: Fix Kconfig indentation
  xen/mcelog: also allow building for 32-bit kernels
  xen/mcelog: add PPIN to record when available
  xen/mcelog: drop __MC_MSR_MCGCAP
  xen/gntdev: Use select for DMA_SHARED_BUFFER
  xen: mm: make xen_mm_init static
  xen: mm: include <xen/xen-ops.h> for missing declarations