mm/memblock: Fix typo in comment of memblock_phys_alloc_try_nid()

memblock_phys_alloc_try_nid function's comments has typo NUMA as MUMA.
Correct this typo.

Signed-off-by: Levi Yun <ppbuk5246@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>