drm/tegra: sor - Remove obsolete comment

According to the DP specification the disparity of the first symbol
should always be negative. It is therefore safe to assume that panels
will conform to that and therefore parameterizing this field should
never be necessary.
Signed-off-by: NThierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/sor.c

@@ -713,7 +713,7 @@ static int tegra_output_sor_enable(struct tegra_output *output)
 		value &= ~SOR_DP_CONFIG_ACTIVE_SYM_POLARITY;
 
 	value |= SOR_DP_CONFIG_ACTIVE_SYM_ENABLE;
-	value |= SOR_DP_CONFIG_DISPARITY_NEGATIVE; /* XXX: don't hardcode? */
+	value |= SOR_DP_CONFIG_DISPARITY_NEGATIVE;
 	tegra_sor_writel(sor, value, SOR_DP_CONFIG_0);
 
 	value = tegra_sor_readl(sor, SOR_DP_AUDIO_HBLANK_SYMBOLS);