V4L/DVB (12394): cx88: Disable xc3028 power management for Geniatech x8000

A user discovered that the Geniatech x8000 encountered a regression when
the xc3028 power management was introduced.  The xc3028 never recovers after
setting the powerdown register, which is probably because the xc3028 reset
GPIO is not properly configured.  Since I do not have access to the hardware
and thus cannot determine the correct GPIO configuration, just disable xc3028
power management on this board, which fixes the regression.

Thanks to user "ritec" for reporting the issue and testing the fix.

Cc: rictec <rictec@netcabo.pt>
Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>