OMAPDSS: OVERLAY: Clean up replication checking

Replication logic for an overlay depends on the color mode in which it is
configured and the video port width of the manager it is connected to.

video port width now held in dss_lcd_mgr_config in the manager's private
data in APPLY. Use this instead of referring to the omap_dss_device connected to
the manager.

Replication is enabled in the case of TV manager, the video_port_width is set to
a default value of 24 for TV manager.

Make the replication checking an overlay function since it's more of an overlay
characteristic than a display characteristic.

Signed-off-by: Archit Taneja <archit@ti.com>