pm_rps: Load helper should stall for last write

This ensures that gpu is quiescent when load helper exits.

Signed-off-by: Jeff McGee <jeff.mcgee@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

tests/pm_rps.c

@@ -207,6 +207,10 @@ static void load_helper_run(void)
 			val++;
 		}
 
+		/* Map buffer to stall for write completion */
+		drm_intel_bo_map(lh.target_buffer, 0);
+		drm_intel_bo_unmap(lh.target_buffer);
+
 		log("load helper sent %u dword writes\n", val);
 	}
 }