[media] smiapp: Replace pll_flags quirk with more generic init quirk

The pll_flags quirk just returned the extra PLL flags the sensor required,
but the init quirk is far more versatile. It can be used to perform any
extra initialisation needed by the sensor, including allocating memory for
sensor specific struct and creating sensor specific new controls.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>