drm/i915/icl: Handle YCbCr to RGB conversion for BT2020 case

Currently input csc for YCbCR to RGB conversion handles only
BT601 and Bt709. Extending it to support BT2020 as well.

v2: Fixed the co-efficients for LR to FR conversion,
as suggested by Ville.

v3: Fixed Y Pre-offset in case of Full Range YCbCr as suggested
by Ville.

v4: Split the v2 and v3 changes.

v5: Rebase

v6: Fix a rebase fumble.
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NUma Shankar <uma.shankar@intel.com>
Signed-off-by: NShashank Sharma <shashank.sharma@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190628080230.27492-2-uma.shankar@intel.com

drivers/gpu/drm/i915/display/intel_sprite.c

@@ -444,6 +444,18 @@ icl_program_input_csc(struct intel_plane *plane,
 			0x9EF8, 0x7800, 0xABF8,
 			0x0, 0x7800,  0x7ED8,
 		},
+		/*
+		 * BT.2020 full range YCbCr -> full range RGB
+		 * The matrix required is :
+		 * [1.000, 0.000, 1.474,
+		 *  1.000, -0.1645, -0.5713,
+		 *  1.000, 1.8814, 0.0000]
+		 */
+		[DRM_COLOR_YCBCR_BT2020] = {
+			0x7BC8, 0x7800, 0x0,
+			0x8928, 0x7800, 0xAA88,
+			0x0, 0x7800, 0x7F10,
+		},
 	};
 
 	/* Matrix for Limited Range to Full Range Conversion */
@@ -472,6 +484,18 @@ icl_program_input_csc(struct intel_plane *plane,
 			0x8888, 0x7918, 0xADA8,
 			0x0, 0x7918,  0x6870,
 		},
+		/*
+		 * BT.2020 Limited range YCbCr -> full range RGB
+		 * The matrix required is :
+		 * [1.164, 0.000, 1.678,
+		 *  1.164, -0.1873, -0.6504,
+		 *  1.164, 2.1417, 0.0000]
+		 */
+		[DRM_COLOR_YCBCR_BT2020] = {
+			0x7D70, 0x7950, 0x0,
+			0x8A68, 0x7950, 0xAC00,
+			0x0, 0x7950, 0x6890,
+		},
 	};
 	const u16 *csc;