media: i2c: adv748x: Fix pixel rate values

The pixel rate, as reported by the V4L2_CID_PIXEL_RATE control, must
include both horizontal and vertical blanking. Both the AFE and HDMI
receiver program it incorrectly:

- The HDMI receiver goes to the trouble of removing blanking to compute
the rate of active pixels. This is easy to fix by removing the
computation and returning the incoming pixel clock rate directly.

- The AFE performs similar calculation, while it should simply return
the fixed pixel rate for analog sources, mandated by the ADV748x to be
14.3180180 MHz.

[Niklas: Update AFE fixed pixel rate]

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>