[media] dvb-usb: use %*ph to dump small buffers

[crope@iki.fi: fix trivial merge conflict]
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>