disp: msm: dsi: Add a new function to get drm_panel

A new API to get drm_panel from dsi_display.
The drm_panel was defined as a member of drm_connector.
When doing connector initialize, can set drm_panel to
drm_connector. So this API is needed to get drm_panel
from dsi_dsiplay.

Change-Id: I0ec9de5a9407085048a8fef421b7b28d466085ed
Signed-off-by: Yuan Zhao <yzhao@codeaurora.org>

msm/dsi/dsi_display.h

@@ -585,6 +585,15 @@ int dsi_display_set_tpg_state(struct dsi_display *display, bool enable);
 int dsi_display_clock_gate(struct dsi_display *display, bool enable);
 int dsi_dispaly_static_frame(struct dsi_display *display, bool enable);
 
+/**
+ * dsi_display_get_drm_panel() - get drm_panel from display.
+ * @display:            Handle to display.
+ * Get drm_panel which was inclued in dsi_display's dsi_panel.
+ *
+ * Return: drm_panel/NULL.
+ */
+struct drm_panel *dsi_display_get_drm_panel(struct dsi_display *display);
+
 /**
  * dsi_display_enable_event() - enable interrupt based connector event
  * @connector:          Pointer to drm connector structure