Cycles: Fix OpenCL compilation failure after recent color changes

It is really confusing to have some functions available in some devices
and not on another devices.

intern/cycles/kernel/svm/svm_image.h

@@ -174,7 +174,7 @@ ccl_device float4 svm_image_texture(KernelGlobals *kg, int id, float x, float y,
 	}
 
 	if(srgb) {
-		r = color_srgb_to_scene_linear(r);
+		r = color_srgb_to_scene_linear_v4(r);
 	}
 
 	return r;