ovl: fix file leak in ovl_real_fdget_meta()

ovl_open_realfile() is wrongly called twice after conversion to
new struct fd.

Fixes: 88a2f646 ("struct fd: representation change")
Reported-by:  <syzbot+d9efec94dcbfa0de1c07@syzkaller.appspotmail.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>