V4L/DVB (3967): Pwc-dec23 oops fix

drivers/media/video/pwc/pwc-dec23.c: In function `pwc_dec23_decompress':
drivers/media/video/pwc/pwc-dec23.c:885: warning: null argument where non-null required (arg 2)

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>