drm: bridge: thc63: Restrict modes based on hardware operating frequency

The THC63LVD1024 is restricted to a pixel clock frequency in the range
of 8 to 135 MHz. Implement the bridge .mode_valid() operation
accordingly.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Tested-by: Jacopo Mondi <jacopo+renesas@jmondi.org>