[media] au0828: rework GPIO management for HVR-950q

Restructure the way we bring the various GPIOs out of reset.  In particular:

1.  we only need to setup the GPIOs as outputs once
2.  there's no point in writing 0x40 to register 0x00 since that's the EEPROM
    write protect and already it's configured as an input
3.  Separate out the act of enabling the power supply and bringing the tuner
    and demod out of reset.  If you don't then the chip may not be properly
    enabled (as the power supply is still ramping up when the chip comes
    out of reset).  This can result in probing failures.

Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>