OMAPFB: remove early mem alloc from old omapfb

arch/arm/plat-omap/fb.c contains code to alloc omapfb buffers at early
boot time according to information given from the bootloader or board
file.

This code isn't currently used by any board, and is anyway something
that the newer vram.c could handle. So remove the alloc code and in
later patches make old omapfb driver use vram.c.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>