drm/radeon: rework GPU reset on cayman/TN

Update the code to better match the recommended
programming sequence for soft reset.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/evergreen.c b/drivers/gpu/drm/radeon/evergreen.c
index 903cc54..48967a9 100644
--- a/drivers/gpu/drm/radeon/evergreen.c
+++ b/drivers/gpu/drm/radeon/evergreen.c
@@ -2327,7 +2327,7 @@
 	return radeon_ring_test_lockup(rdev, ring);
 }
 
-static void evergreen_print_gpu_status_regs(struct radeon_device *rdev)
+void evergreen_print_gpu_status_regs(struct radeon_device *rdev)
 {
 	dev_info(rdev->dev, "  GRBM_STATUS               = 0x%08X\n",
 		RREG32(GRBM_STATUS));