drm/radeon/benchmark: make sure bo blit copy exists before using it

Fixes a segfault on asics without a blit callback.

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=62239

Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/radeon/radeon_benchmark.c

@@ -135,13 +135,15 @@ static void radeon_benchmark_move(struct radeon_device *rdev, unsigned size,
 						     sdomain, ddomain, "dma");
 	}
 
-	time = radeon_benchmark_do_move(rdev, size, saddr, daddr,
-					RADEON_BENCHMARK_COPY_BLIT, n);
-	if (time < 0)
-		goto out_cleanup;
-	if (time > 0)
-		radeon_benchmark_log_results(n, size, time,
-					     sdomain, ddomain, "blit");
+	if (rdev->asic->copy.blit) {
+		time = radeon_benchmark_do_move(rdev, size, saddr, daddr,
+						RADEON_BENCHMARK_COPY_BLIT, n);
+		if (time < 0)
+			goto out_cleanup;
+		if (time > 0)
+			radeon_benchmark_log_results(n, size, time,
+						     sdomain, ddomain, "blit");
+	}
 
 out_cleanup:
 	if (sobj) {