mm/huge_memory.c: remove unnecessary local variable ret2

mm/huge_memory.c: remove unnecessary local variable ret2

There is no need to use a new local variable ret2 to get the return
value of handle_userfault().  Use ret directly to make code more
succinct.

Link: https://lkml.kernel.org/r/20210210072409.60587-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>