[media] hdpvr: Fix memory leak in debug

cppcheck reported memory leak in device_authorizatio()
within hdpvr-core.c.
When the debug option is specified and the code jump to
"unlock:" label, print_buf was not freed.
Confirm the module succesfully compiled without error.

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>