USB: iowarrior.c: fix NULL dereference

Am Montag, 19. 2007 10:25 schrieb Adrian Bunk:
> The Coverity checker spotted the following NULL dereference:

And this fixes an oops upon allocation failures.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>