media: i2c: imx219: Scale the pixel clock rate for the 640x480 mode

The 640x480 mode uses a special binning mode for high framerate operation where
the pixel rate is effectively doubled. Account for this when setting up the
pixel clock rate, and applying the vblank and exposure controls.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>