drm/panel: otm8009a: remove hack to force commands in HS

The panel is able to receive commands in LP. The current hack to
force backlight commands in HS was due to workaround an incorrect
settings on DSI controller that prevents sending LP commands while
video out was active.

Remove the hack that forces HS commands.

Changes in v2:
  - Added my signed-off
Signed-off-by: Antonio Borneo <antonio.borneo@st.com>
Signed-off-by: Yannick Fertre <yannick.fertre@st.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200922074242.28719-1-yannick.fertre@st.com

drivers/gpu/drm/panel/panel-orisetech-otm8009a.c

@@ -99,20 +99,6 @@ static void otm8009a_dcs_write_buf(struct otm8009a *ctx, const void *data,
 		dev_warn(ctx->dev, "mipi dsi dcs write buffer failed\n");
 }
 
-static void otm8009a_dcs_write_buf_hs(struct otm8009a *ctx, const void *data,
-				      size_t len)
-{
-	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
-
-	/* data will be sent in dsi hs mode (ie. no lpm) */
-	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
-
-	otm8009a_dcs_write_buf(ctx, data, len);
-
-	/* restore back the dsi lpm mode */
-	dsi->mode_flags |= MIPI_DSI_MODE_LPM;
-}
-
 #define dcs_write_seq(ctx, seq...)			\
 ({							\
 	static const u8 d[] = { seq };			\
@@ -400,7 +386,7 @@ static int otm8009a_backlight_update_status(struct backlight_device *bd)
 		 */
 		data[0] = MIPI_DCS_SET_DISPLAY_BRIGHTNESS;
 		data[1] = bd->props.brightness;
-		otm8009a_dcs_write_buf_hs(ctx, data, ARRAY_SIZE(data));
+		otm8009a_dcs_write_buf(ctx, data, ARRAY_SIZE(data));
 
 		/* set Brightness Control & Backlight on */
 		data[1] = 0x24;
@@ -412,7 +398,7 @@ static int otm8009a_backlight_update_status(struct backlight_device *bd)
 
 	/* Update Brightness Control & Backlight */
 	data[0] = MIPI_DCS_WRITE_CONTROL_DISPLAY;
-	otm8009a_dcs_write_buf_hs(ctx, data, ARRAY_SIZE(data));
+	otm8009a_dcs_write_buf(ctx, data, ARRAY_SIZE(data));
 
 	return 0;
 }