[media] Kconfig: fix breakages when DVB_CORE is not selected

On some weird randconfigs, it is possible to select DVB
drivers, without having the DVB_CORE:

CONFIG_DVB_AU8522=m
CONFIG_DVB_AU8522_V4L=m
CONFIG_DVB_TUNER_DIB0090=m

This was never supposed to work, but changeset 22a613e8
("[media] dvb_frontend: merge duplicate dvb_tuner_ops.release implementations")
caused it to be exposed:

   drivers/built-in.o: In function `fc0011_attach':
   (.text+0x1598fb): undefined reference to `dvb_tuner_simple_release'
   drivers/built-in.o:(.rodata+0x55e58): undefined reference to `dvb_tuner_simple_release'
   drivers/built-in.o:(.rodata+0x57398): undefined reference to `dvb_tuner_simple_release'

Fixes: 22a613e8 ("[media] dvb_frontend: merge duplicate dvb_tuner_ops.release implementations")
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>