media: tunner: xc5000: Refactor firmware load

Make sure the firmware is released when we leave
xc_load_fw_and_init_tuner()

This change makes smatch happy:
drivers/media/tuners/xc5000.c:1213 xc_load_fw_and_init_tuner() warn: 'fw' from request_firmware() not released on lines: 1213.

Cc: Shuah Khan <shuah.kh@samsung.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>