OMAP2PLUS: DSS2: FEATURES: DISPC overlay code cleanup

Add dss_features and register fields to incorporate changes in DISPC pipelines
between OMAP3 and OMAP4.

Register fields added: FEAT_REG_HORIZONTALACCU, FEAT_REG_VERTICALACCU
DSS Features added: FEAT_LINEBUFFERSPLIT, FEAT_ROWREPEATENABLE, FEAT_RESIZECONF

_dispc_set_scaling() and _dispc_set_rotation_attrs() have been cleaned up.

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