Always use raster pipeline for radial gradients

Change-Id: Id4c9ed45c28becf0e25ed9ff1b3380c7ca65aa4b
Reviewed-on: https://skia-review.googlesource.com/25363
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>

src/shaders/gradients/SkRadialGradient.cpp

@@ -367,8 +367,7 @@ bool SkRadialGradient::onIsRasterPipelineOnly() const {
 #ifdef SK_SUPPORT_LEGACY_RADIAL_GRADIENT
     return false;
 #else
-    // We have a clamp fast path; everything else -> RP.
-    return fTileMode != SkShader::kClamp_TileMode;
+    return true;
 #endif
 }