ARM: OMAP2+: Make display related init into device_initcall

We can initialize almost everything at normal module_init time with
ti-sysc except for clocks and timers. To prepare for that, let's make
display init into device_initcall as otherwise we'll be calling
of_platform_populate() before the parent has probed.

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>