mm/memory.c: fix typo in __do_fault() comment

It's "pte_alloc_one", not "pte_alloc_pne". Let's fix that.

Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Link: http://lkml.kernel.org/r/20200818104339.5310-1-yanfei.xu@windriver.com


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>