OMAP2PLUS: DSS2: Use dss features to get clock source names of current OMAP

Clock source names vary across OMAP2/3 and OMAP4, the clock source enum
names have been made generic in the driver, but for purposes of debugging
and dumping clock sources, it is better to preserve the actual TRM name of
the clock.

Introduce a dss feature function 'dss_feat_get_clk_source_name()' which
returns a string with the TRM clock name for the current OMAP in use. The OMAP
specific name is printed along the generic name within brackets.

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

drivers/video/omap2/dss/dss_features.h

@@ -57,6 +57,7 @@ enum omap_display_type dss_feat_get_supported_displays(enum omap_channel channel
 enum omap_color_mode dss_feat_get_supported_color_modes(enum omap_plane plane);
 bool dss_feat_color_mode_supported(enum omap_plane plane,
 		enum omap_color_mode color_mode);
+const char *dss_feat_get_clk_source_name(enum dss_clk_source id);
 
 bool dss_has_feature(enum dss_feat_id id);
 void dss_feat_get_reg_field(enum dss_feat_reg_field id, u8 *start, u8 *end);