Fix a dumb typo - use of & instead of &&

We managed to lose O_DIRECTORY testing due to a stupid typo in commit
1f36f774b2 ("Switch !O_CREAT case to use of do_last()")

Reported-by: Walter Sheets <w41ter@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>