v4l: xilinx-gamma: Add check for max width and height

v4l: xilinx-gamma: Add check for max width and height

Patch adds support to get maximum width and height from device tree
property. If the parameters are not present then the IP sets the
maximum size of 8192x4320. It then uses this value to clamp width
and height instead of fixed max value while setting format.

It also corrects the minimum width and height parameters.

Signed-off-by: Vishal Sagar <vishal.sagar@xilinx.com>
Reviewed-by: Hyun Kwon <hyun.kwon@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>