Revert of Code's more readable when SkPMFloat is an Sk4f.

src/effects/SkColorMatrixFilter.cpp

Index: src/effects/SkColorMatrixFilter.cpp
diff --git a/src/effects/SkColorMatrixFilter.cpp b/src/effects/SkColorMatrixFilter.cpp
index 196ebd0f251f5ef1f5145179850758de9f90332a..a20c65a0a53238f802a87b17f8fda1ab36c0ddc0 100644
--- a/src/effects/SkColorMatrixFilter.cpp
+++ b/src/effects/SkColorMatrixFilter.cpp
@@ -269,7 +269,7 @@
 
 static Sk4f unpremul(const SkPMFloat& pm) {
     float scale = 255 / pm.a(); // candidate for fast/approx invert?
-    return pm * Sk4f(scale, scale, scale, 1);
+    return Sk4f(pm) * Sk4f(scale, scale, scale, 1);
 }
 
 static Sk4f clamp_0_255(const Sk4f& value) {