[PATCH]videobuf-core.c: add pointer check

["Figo.zhang" <figo1802@gmail.com>]

add poiter check for videobuf_queue_core_init().

any guys who write a v4l driver, pass a NULL pointer or a non-inintial
pointer to the first parameter such as videobuf_queue_sg_init() , it 
would be crashed.

Signed-off-by: Figo.zhang <figo1802@gmail.com>
--- 
drivers/media/video/videobuf-core.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/drivers/media/video/videobuf-core.c b/drivers/media/video/videobuf-core.c
index b7b0584..5f41fd9 100644
--- a/drivers/media/video/videobuf-core.c
+++ b/drivers/media/video/videobuf-core.c
@@ -118,6 +118,7 @@ void videobuf_queue_core_init(struct videobuf_queue *q,
 			 void *priv,
 			 struct videobuf_qtype_ops *int_ops)
 {
+	BUG_ON(!q);
 	memset(q, 0, sizeof(*q));
 	q->irqlock   = irqlock;
 	q->dev       = dev;