x86, efi: Ensure that the entirity of a region is mapped

It's possible for init_memory_mapping() to fail to map the entire region
if it crosses a boundary, so ensure that we complete the mapping.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Link: http://lkml.kernel.org/r/1304623186-18261-5-git-send-email-mjg@redhat.com


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>