OMAP: omap4sdp: move display init from board file to dss-common.c

OMAP: omap4sdp: move display init from board file to dss-common.c

Device tree support for omapdss is still some way in the future.  In an
effort to get a minimal DSS support for DT enabled kernel on selected
OMAP4 boards, we'll go for a temporary solution: We will call the same
non-DT omapdss setup code for OMAP4 SDP and Pandaboards from
board-generic.c, thus enabling DSS for those boards.

This patch moves the display setup code from board-4430sdp.c to
dss-common.c. dss-common.c will be called by the board-4430sdp.c when
running on non-DT kernel, and by board-generic.c when running on DT
enabled kernel.

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