drm/radeon: add runtime PM support (v2)

This hooks radeon up to the runtime PM system to enable
dynamic power management for secondary GPUs in switchable
and powerxpress laptops.

v2: agd5f: clean up, add module parameter

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/radeon_atpx_handler.c b/drivers/gpu/drm/radeon/radeon_atpx_handler.c
index d96070b..6153ec1 100644
--- a/drivers/gpu/drm/radeon/radeon_atpx_handler.c
+++ b/drivers/gpu/drm/radeon/radeon_atpx_handler.c
@@ -59,6 +59,10 @@
 	u16 mux;
 } __packed;
 
+bool radeon_is_px(void) {
+	return radeon_atpx_priv.atpx_detected;
+}
+
 /**
  * radeon_atpx_call - call an ATPX method
  *