AF903x/IT913x demod provides clock source(s). It seems that this
clock source is used for integrated RF tuner of IT913x. It is
enabled by default, but firmware disables it automatically when
suspend is requested (suspend_flag (0x004c) + trigger_ofsm
(0x0000)). Automatic disable behavior seems to be similar for both
AF903x and IT913x I tested, though there is no likely any real
clock user in a case of AF903x.

Cc: Bimow Chen <Bimow.Chen@ite.com.tw>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>