SCSI: scsi_lib: fix potential NULL dereference

commit 03b14708 upstream.

Stanse found a potential NULL dereference in scsi_kill_request.

Instead of triggering BUG() in 'if (unlikely(cmd == NULL))' branch,
the kernel will Oops earlier on cmd dereference.

Move the dereferences after the if.

[ WT: starget is not set in 2.6.27 ]

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Willy Tarreau <w@1wt.eu>