drivers: video: ov7670: improve resolution init code

Improve resolution init code for OV7670 driver, to properly program the
full set of registers needed to realize a given output resolution. The
settings for these registers are based on those used in the MCUX SDK
driver, which are derived from the resolution register settings given in
the OV7670 programming guide, with a different configuration for the
CLKSRC and DBLV registers used for the input clock.

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>