remove unneeded SK_SUPPORT_LEGACY_MIPMAP_EFFECTIVE_SCALE guard

src/core/SkBitmapProcState.cpp

Index: src/core/SkBitmapProcState.cpp
diff --git a/src/core/SkBitmapProcState.cpp b/src/core/SkBitmapProcState.cpp
index 69c2ea19be30a6e7a97b5a1a6d5481e1917300da..720a30f05c4a72b77365237c929755e0c1a4cf17 100644
--- a/src/core/SkBitmapProcState.cpp
+++ b/src/core/SkBitmapProcState.cpp
@@ -101,11 +101,7 @@ static bool valid_for_filtering(unsigned dimension) {
 static SkScalar effective_matrix_scale(const SkMatrix& mat) {
     SkScalar dx = SkVector::Length(mat.getScaleX(), mat.getSkewY());
     SkScalar dy = SkVector::Length(mat.getSkewX(), mat.getScaleY());
-#ifdef SK_SUPPORT_LEGACY_MIPMAP_EFFECTIVE_SCALE
-    return SkMaxScalar(dx, dy);
-#else
     return SkScalarSqrt(dx * dy);
-#endif
 }
 
 // Check to see that the size of the bitmap that would be produced by