drm/rockchip: removed optional dummy encoder mode_fixup function.

mode_fixup function for encoder drivers became optional with patch
http://patchwork.freedesktop.org/patch/msgid/1455106522-32307-1-git-send-email-palminha@synopsys.com

This patch set nukes all the dummy mode_fixup implementations.

(made on top of Daniel topic/drm-misc branch)
Signed-off-by: Carlos Palminha <palminha@synopsys.com>
Acked-by: Mark Yao <mark.yao@rock-chips.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/cae559aa2c04a906c21ed5ebe4861f92440e6910.1455540137.git.palminha@synopsys.com

drivers/gpu/drm/rockchip/dw-mipi-dsi.c

@@ -875,13 +875,6 @@ static void dw_mipi_dsi_encoder_disable(struct drm_encoder *encoder)
 	clk_disable_unprepare(dsi->pclk);
 }
 
-static bool dw_mipi_dsi_encoder_mode_fixup(struct drm_encoder *encoder,
-					const struct drm_display_mode *mode,
-					struct drm_display_mode *adjusted_mode)
-{
-	return true;
-}
-
 static void dw_mipi_dsi_encoder_commit(struct drm_encoder *encoder)
 {
 	struct dw_mipi_dsi *dsi = encoder_to_dsi(encoder);
@@ -931,7 +924,6 @@ static void dw_mipi_dsi_encoder_commit(struct drm_encoder *encoder)
 
 static struct drm_encoder_helper_funcs
 dw_mipi_dsi_encoder_helper_funcs = {
-	.mode_fixup = dw_mipi_dsi_encoder_mode_fixup,
 	.commit = dw_mipi_dsi_encoder_commit,
 	.mode_set = dw_mipi_dsi_encoder_mode_set,
 	.disable = dw_mipi_dsi_encoder_disable,