drm/radeon: Only create additional ring debugfs files on Cayman or newer.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=46274

Tested with a Cayman card in a Llano system: The additional files are created
and working for the Cayman card but not created for the CPU's built-in GPU.
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_ring.c

@@ -500,8 +500,11 @@ static char radeon_debugfs_ib_names[RADEON_IB_POOL_SIZE][32];
 int radeon_debugfs_ring_init(struct radeon_device *rdev)
 {
 #if defined(CONFIG_DEBUG_FS)
-	return radeon_debugfs_add_files(rdev, radeon_debugfs_ring_info_list,
-					ARRAY_SIZE(radeon_debugfs_ring_info_list));
+	if (rdev->family >= CHIP_CAYMAN)
+		return radeon_debugfs_add_files(rdev, radeon_debugfs_ring_info_list,
+						ARRAY_SIZE(radeon_debugfs_ring_info_list));
+	else
+		return radeon_debugfs_add_files(rdev, radeon_debugfs_ring_info_list, 1);
 #else
 	return 0;
 #endif