ARM: mach-shmobile: ag5evm: Add LCDC tx_dev field to platform data

Reference the MIPI-DSI transceiver in the LCDC platform data and make
sure it gets registered before the LCDC.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Simon Horman <horms@verge.net.au>