imx: ventana: added DT fixup for GW551x-A video input

imx: ventana: added DT fixup for GW551x-A video input

The GW551x-A revision does not have the CSI0_DATA_EN pin connected, therefore
we need to make sure that signal is not muxed to the CSI_DATA_EN signal
internally and do so by steering it to the unused GPIO5_IO20.

We do this so that the kernel device-tree can properly define the signal for
RevB and beyond boards that do have this hooked up properly and require it.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>