media: dvb-frontends: fix a memory leak bug

In cx24117_load_firmware(), 'buf' is allocated through kmalloc() to hold
the firmware. However, if i2c_transfer() fails, it is not deallocated,
leading to a memory leak bug.

Signed-off-by: Wenwen Wang <wenwen@cs.uga.edu>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>