OMAPDSS: Makefile: move omapfb after panels

omapfb requires the panels to have been probed before omapfb's probe. We
currently manage that by having omapfb in late initcall level. However,
a much simpler way is to just change the makefile so that omapfb is
after the panel drivers.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>