OMAP: DSS2: Add new FEAT definitions for features missing from OMAP2

OMAP2 doesn't have CPR, PRELOAD nor FIR_COEF_V registers. Add new
feature definitions for those, and check the feature before accessing
those registers.

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 3058e24..5be8103 100644
--- a/drivers/video/omap2/dss/dss_features.h
+++ b/drivers/video/omap2/dss/dss_features.h
@@ -52,6 +52,9 @@
 	FEAT_HANDLE_UV_SEPARATE         = 1 << 20,
 	FEAT_ATTR2                      = 1 << 21,
 	FEAT_VENC_REQUIRES_TV_DAC_CLK	= 1 << 22,
+	FEAT_CPR			= 1 << 23,
+	FEAT_PRELOAD			= 1 << 24,
+	FEAT_FIR_COEF_V			= 1 << 25,
 };
 
 /* DSS register field id */