[media] V4L: mt9v022: fix pixel clock

The setup of the pixel clock is done wrong in the mt9v022 driver.
The 'Invert Pixel Clock' bit has to be set to 1 for falling edge
and not for rising. This is not clearly described in the data
sheet.

Tested on pcm037 and pcm027/pcm990.

Signed-off-by: Teresa Gámez <t.gamez@phytec.de>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>