media: uapi: pisp_be_config: Re-sort pisp_be_tiles_config

The order of the members of pisp_be_tiles_config is relevant
as the driver logic assumes 'config' to be at offset 0.

Re-sort the member to match the driver's expectations.

Fixes: c6c49bac ("media: uapi: Add Raspberry Pi PiSP Back End uAPI")
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>