V4L/DVB (7832): xc5000: MEDIA_TUNER_XC5000 must select FW_LOADER

Fix the following build error:

drivers/built-in.o: In function `xc_load_fw_and_init_tuner':
xc5000.c:(.text+0x2dacd): undefined reference to `request_firmware'
xc5000.c:(.text+0x2daf0): undefined reference to `release_firmware'
xc5000.c:(.text+0x2db85): undefined reference to `release_firmware'
make[1]: *** [.tmp_vmlinux1] Error 1

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>