Cycles/Windows: Fix over estimation of System RAM.

`system_physical_ram` reported 1024x more System RAM than what
was actually available.

intern/cycles/util/util_system.cpp

@@ -357,7 +357,7 @@ size_t system_physical_ram()
   MEMORYSTATUSEX ram;
   ram.dwLength = sizeof(ram);
   GlobalMemoryStatusEx(&ram);
-  return ram.ullTotalPhys * 1024;
+  return ram.ullTotalPhys;
 #elif defined(__APPLE__)
   uint64_t ram = 0;
   size_t len = sizeof(ram);