[media] hdpvr: reduce memory footprint when debugging

There is no need to use hex_dump_to_buffer() since we have a kernel helper to
dump up to 64 bytes just via printk().

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>