Cycles / CUDA: Workaround to make sm_52 (Maxwell) cards work.

* sm_52 can run a sm_50 kernel, so tell runtime detection to use that until we build a dedicated sm_52 kernel.

intern/cycles/device/device_cuda.cpp

@@ -202,6 +202,10 @@ public:
 		/* compute cubin name */
 		int major, minor;
 		cuDeviceComputeCapability(&major, &minor, cuDevId);
+		
+		/* workaround to make sm_52 cards work, until we bundle kernel */
+		if(major == 5 && minor == 2)
+			minor = 0;
 
 		/* attempt to use kernel provided with blender */
 		string cubin;