stop using SkScalarMul

BUG=skia:

Change-Id: Ie41d8665a1c62ba8eddc93d8cfefaf64ddc52ff8
Reviewed-on: https://skia-review.googlesource.com/8411
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/bench/ImageFilterCollapse.cpp b/bench/ImageFilterCollapse.cpp
index d85d1de..ce27f06 100644
--- a/bench/ImageFilterCollapse.cpp
+++ b/bench/ImageFilterCollapse.cpp
@@ -98,7 +98,7 @@
 };
 
 static sk_sp<SkColorFilter> make_brightness(float amount) {
-    SkScalar amount255 = SkScalarMul(amount, SkIntToScalar(255));
+    SkScalar amount255 = amount * 255;
     SkScalar matrix[20] = { 1, 0, 0, 0, amount255,
                             0, 1, 0, 0, amount255,
                             0, 0, 1, 0, amount255,