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.c b/drivers/video/omap2/dss/dss_features.c
index 5be5eb0..6460b0a 100644
--- a/drivers/video/omap2/dss/dss_features.c
+++ b/drivers/video/omap2/dss/dss_features.c
@@ -294,7 +294,8 @@
 		FEAT_GLOBAL_ALPHA | FEAT_PRE_MULT_ALPHA |
 		FEAT_MGR_LCD2 | FEAT_GLOBAL_ALPHA_VID1 |
 		FEAT_CORE_CLK_DIV | FEAT_LCD_CLK_SRC |
-		FEAT_DSI_DCS_CMD_CONFIG_VC | FEAT_DSI_VC_OCP_WIDTH,
+		FEAT_DSI_DCS_CMD_CONFIG_VC | FEAT_DSI_VC_OCP_WIDTH |
+		FEAT_DSI_GNQ,
 
 	.num_mgrs = 3,
 	.num_ovls = 3,