msm: cpp: Create buffer queue only if it is missing

When CPP kernel driver receives IOCTL command
VIDIOC_MSM_CPP_ENQUEUE_STREAM_BUFF_INFO it crates new
queue for the current stream. If such command is received
more than once, CPP driver will create more than one queue.
To avoid this, it will check first, whether the queue is
not already created and allocate it if necessary.

Change-Id: I1eebb32cecb9a0a9a9d4e821ea946df6803ec5a0
Signed-off-by: Iliya Varadzhakov <ivarad@codeaurora.org>