ecore-drm2: Add API function to retrieve output user data

With the rework of Ecore_Evas drm engine, we need to get the
ecore_evas itself in the pageflip callback so we have to reassign
output->user_data to the ecore_evas which we can then use to retrieve
via this function

This is needed as the pageflip callback will pass us the output on
which the pageflip completed.

@feature

Signed-off-by: Chris Michael <cp.michael@samsung.com>

src/lib/ecore_drm2/Ecore_Drm2.h

@@ -792,6 +792,18 @@ EAPI Eina_Bool ecore_drm2_output_rotation_set(Ecore_Drm2_Output *output, int rot
  */
 EAPI void ecore_drm2_output_user_data_set(Ecore_Drm2_Output *o, void *data);
 
+/**
+ * Get the user data for a given output
+ *
+ * @param output The output to get user data for
+ *
+ * @return The user data associated with given output
+ *
+ * @ingroup Ecore_Drm2_Output_Group
+ * @since 1.21
+ */
+EAPI void *ecore_drm2_output_user_data_get(Ecore_Drm2_Output *output);
+
 /**
  * Get the subpixel state of the output
  * @param output the output

src/lib/ecore_drm2/ecore_drm2_outputs.c

@@ -1456,6 +1456,13 @@ ecore_drm2_output_user_data_set(Ecore_Drm2_Output *o, void *data)
    o->user_data = data;
 }
 
+EAPI void *
+ecore_drm2_output_user_data_get(Ecore_Drm2_Output *output)
+{
+   EINA_SAFETY_ON_NULL_RETURN_VAL(output, NULL);
+   return output->user_data;
+}
+
 EAPI void
 ecore_drm2_output_gamma_set(Ecore_Drm2_Output *output, uint16_t size, uint16_t *red, uint16_t *green, uint16_t *blue)
 {