[PATCH] Fix sequencer missing negative bound check

'int dev' came out of an 'unsigned char *' - as such, it will not get
a negative value. Thanks Valdis.

Signed-off-by: Eugene Teo <eugene.teo@eugeneteo.net>
Cc: Jaroslav Kysela <perex@suse.cz>
Acked-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>