V4L/DVB (5240): Qt1010: use i2c_gate_ctrl where appropriate

This patch adds calls to i2c_gate_ctrl in the qt1010 dvb tuner module,
while removing the temporary hack in au6610 and gl861.
Tested successfully against fi-Oulu frequencies with
MSI Megasky 580 GL861 and Sigmatek DVB-110 AU6610.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>