OMAP: DSS2: DSI: Get number of DSI data lanes using DSI_GNQ register

On OMAP3, the DSI module has 2 data lanes. On OMAP4, DSI1 has 4 data lanes
and DSI2 has 2 data lanes. Introduce function dsi_get_num_data_lanes() which
returns the number of data lanes on the dsi interface, introduce function
dsi_get_num_data_lanes_dssdev() which returns the number of data lanes used by
the omap_dss_device connected to the lanes.

Use the DSI_GNQ register on OMAP4 to get the number of data lanes, modify
dsi.c to use the number of lanes and the extra data lanes on DSI1.

Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/omap2/dss/dss_features.h b/drivers/video/omap2/dss/dss_features.h
index 857162b..ff2cf33 100644
--- a/drivers/video/omap2/dss/dss_features.h
+++ b/drivers/video/omap2/dss/dss_features.h
@@ -47,6 +47,7 @@
 	FEAT_DSI_DCS_CMD_CONFIG_VC	= 1 << 15,
 	FEAT_DSI_VC_OCP_WIDTH		= 1 << 16,
 	FEAT_DSI_REVERSE_TXCLKESC	= 1 << 17,
+	FEAT_DSI_GNQ			= 1 << 18,
 };
 
 /* DSS register field id */