mm/nommu.c: delete duplicated words

Drop the repeated word "that" in two places.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Link: http://lkml.kernel.org/r/20200801173822.14973-9-rdunlap@infradead.org


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