vfs: add missing check for __O_TMPFILE in fcntl_init()

As comment in include/uapi/asm-generic/fcntl.h described, when
introducing new O_* bits, we need to check its uniqueness in
fcntl_init().  But __O_TMPFILE bit is missing.  So fix it.

Change-Id: I372d41d2bc15b007595eaf763e200c4c06de177f
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>