disp: msm: add inverted display brightness value property

In general the brightness value, the first parameter is low byte and
the second is high byte, but some DDIC invert, so add inverted display
brightness value property.

Change-Id: I8bf5631bb66096bd28529c53643e358afffce18e
Signed-off-by: Wenjun Zhang <wjzhan@codeaurora.org>

msm/dsi/dsi_panel.c

@@ -506,6 +506,9 @@ static int dsi_panel_update_backlight(struct dsi_panel *panel,
 
 	dsi = &panel->mipi_device;
 
+	if (panel->bl_config.bl_inverted_dbv)
+		bl_lvl = (((bl_lvl & 0xff) << 8) | (bl_lvl >> 8));
+
 	rc = mipi_dsi_dcs_set_display_brightness(dsi, bl_lvl);
 	if (rc < 0)
 		DSI_ERR("failed to update dcs backlight:%d\n", bl_lvl);
@@ -2183,6 +2186,9 @@ static int dsi_panel_parse_bl_config(struct dsi_panel *panel)
 		panel->bl_config.brightness_max_level = val;
 	}
 
+	panel->bl_config.bl_inverted_dbv = utils->read_bool(utils->data,
+		"qcom,mdss-dsi-bl-inverted-dbv");
+
 	if (panel->bl_config.type == DSI_BACKLIGHT_PWM) {
 		rc = dsi_panel_parse_bl_pwm_config(panel);
 		if (rc) {