ov8830: adjust sensor mode for 19.2 MHz ext clock (from 24 MHz)

ov8830: adjust sensor mode for 19.2 MHz ext clock (from 24 MHz)

BZ: 16972

Reference design from Omnivision uses 24 MHz clock, but the
Red Hook Bay allows using only 38.4/n MHz where n is an integer.
Modify the PLL settings so that the internal frequencies
correspond to the original mode but with 19.2 MHz external clock.

Change-Id: I559247a685681f8a773378c862ba139517b4a7bd
Signed-off-by: Tuukka Toivonen <tuukka.toivonen@intel.com>
Reviewed-on: http://android.intel.com:8080/32615
Reviewed-by: Koski, Anttu <anttu.koski@intel.com>
Tested-by: Koski, Anttu <anttu.koski@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>