media: ov08x40: Fix hblank out of range issue

The HTS value cannot be directly compared to the sensor's output
size. It needs to be converted to an absolute time unit.
Additionally, the hblank value need to be modified as it was
previous invalid.

Signed-off-by: Jason Chen <jason.z.chen@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>