drm/radeon/kms: add a radeon asic callback for mc idle

Required for future functionality.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/rs690.c b/drivers/gpu/drm/radeon/rs690.c
index 4f24a0f..29fc8b1 100644
--- a/drivers/gpu/drm/radeon/rs690.c
+++ b/drivers/gpu/drm/radeon/rs690.c
@@ -31,7 +31,7 @@
 #include "atom.h"
 #include "rs690d.h"
 
-static int rs690_mc_wait_for_idle(struct radeon_device *rdev)
+int rs690_mc_wait_for_idle(struct radeon_device *rdev)
 {
 	unsigned i;
 	uint32_t tmp;