media: i2c: Add support for new frequencies to ov7251

The OV7251 sensor is used as the IR camera sensor on the Microsoft
Surface line of tablets; this provides a 19.2MHz external clock, and
the Windows driver for this sensor configures a 319.2MHz link freq to
the CSI-2 receiver. Add the ability to support those rate to the
driver by defining a new set of PLL configs.

Signed-off-by: Daniel Scally <djrscally@gmail.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>