drm/i915: Shrink cnl_ddi_buf_trans

All the values we put into the CNL buf_trans tables fit into 8 bits.
So switch over to u8 from the u32 we use currently.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170918182604.9519-4-ville.syrjala@linux.intel.comReviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_ddi.c

@@ -354,11 +354,11 @@ static const struct bxt_ddi_buf_trans bxt_ddi_translations_hdmi[] = {
 };
 
 struct cnl_ddi_buf_trans {
-	u32 dw2_swing_sel;
-	u32 dw7_n_scalar;
-	u32 dw4_cursor_coeff;
-	u32 dw4_post_cursor_2;
-	u32 dw4_post_cursor_1;
+	u8 dw2_swing_sel;
+	u8 dw7_n_scalar;
+	u8 dw4_cursor_coeff;
+	u8 dw4_post_cursor_2;
+	u8 dw4_post_cursor_1;
 };
 
 /* Voltage Swing Programming for VccIO 0.85V for DP */