[media] au8028: Fix cleanup on kzalloc fail

Free what was allocated if there is a failure allocating
transfer buffers.

Stop the feed on a start feed error.  The stop feed is not always called
if start feed fails.  If the feed is not stopped on error, then the driver
will be stuck so that it can never start feeding again.

[m.chehab@samsung.com: CodingStyle cleanup]
Signed-off-by: Tim Mester <tmester@ieee.org>
Acked-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>