Under some conditions, mmu_notifier_register() will fail to register a
mmu_notifier.  Fix the GRU driver to correctly handle these failures.
Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>