media: i2c: Support 19.2MHz input clock in ov8865

The ov8865 driver as written expects a 24MHz input clock, but the sensor
is sometimes found on x86 platforms with a 19.2MHz input clock supplied.
Add a set of PLL configurations to the driver to support that rate too.
As ACPI doesn't auto-configure the clock rate, check for a clock-frequency
during probe and set that rate if one is found.
Signed-off-by: Daniel Scally <djrscally@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>