Cleanup.

src/renderer_mtl.mm

@@ -2017,6 +2017,8 @@ namespace bgfx { namespace mtl
 			case MTLDataTypeFloat4x4:
 				return UniformType::Mat4;
 
+			default:
+				break;
 		};
 
 		BX_CHECK(false, "Unrecognized Mtl Data type 0x%04x.", _type);