[CIFS] Fix CIFS readdir access denied when SE Linux enabled

CIFS had one path in which dentry was instantiated before the corresponding
inode metadata was filled in.

Fixes Redhat bugzilla bug #163493

Signed-off-by: Steve French <sfrench@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Acked-by: Dave Kleikamp <shaggy@austin.ibm.com>