smb: client: fix file open check in __cifs_unlink()

smb: client: fix file open check in __cifs_unlink()

Fix the file open check to decide whether or not silly-rename the file
in SMB2+.

Fixes: c5ea3065586d ("smb: client: fix data loss due to broken rename(2)")
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Cc: Frank Sorenson <sorenson@redhat.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: linux-cifs@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>