mm: use false for bool variable

Fixes coccicheck warnings:

  mm/zbud.c:246:1-20: WARNING: Assignment of 0/1 to bool variable
  mm/mremap.c:777:2-8: WARNING: Assignment of 0/1 to bool variable
  mm/huge_memory.c:525:9-10: WARNING: return of 0/1 in function 'is_transparent_hugepage' with return type bool

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1586835930-47076-1-git-send-email-zou_wei@huawei.com


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