media: it913x: init tuner on attach

commit 01b461bb upstream.

That register is needed to program very first in order to operate
correctly.

[crope@iki.fi: returned sequence back, removed sleep, moved reg
write earlier to prevent populating tuner ops in case of failure]

Signed-off-by: Bimow Chen <Bimow.Chen@ite.com.tw>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>