V4L/DVB (11991): buf-core.c: add pointer check
V4L/DVB (11991): buf-core.c: add pointer check

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 <1dadb53ceec98c527344000c6a2ae30839312d78@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <ad86ba2154032c9f55743a190faa2459a9d61d42@redhat.com>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs