Unify some SkNx code

src/effects/gradients/SkRadialGradient.cpp

Index: src/effects/gradients/SkRadialGradient.cpp
diff --git a/src/effects/gradients/SkRadialGradient.cpp b/src/effects/gradients/SkRadialGradient.cpp
index 52d06392e1b39085f322b88eb9a2c696cf376a32..d734aa056a4ad6e96455d2c7692c727cd447c706 100644
--- a/src/effects/gradients/SkRadialGradient.cpp
+++ b/src/effects/gradients/SkRadialGradient.cpp
@@ -307,7 +307,7 @@ void shadeSpan_radial_clamp2(SkScalar sfx, SkScalar sdx, SkScalar sfy, SkScalar
             dR = dR + ddR;
 
             uint8_t fi[4];
-            dist.toBytes(fi);
+            SkNx_cast<uint8_t>(dist).store(fi);
 
             for (int i = 0; i < 4; i++) {
                 *dstC++ = cache[toggle + fi[i]];
@@ -319,7 +319,7 @@ void shadeSpan_radial_clamp2(SkScalar sfx, SkScalar sdx, SkScalar sfy, SkScalar
             Sk4f dist = Sk4f::Min(fast_sqrt(R), max);
 
             uint8_t fi[4];
-            dist.toBytes(fi);
+            SkNx_cast<uint8_t>(dist).store(fi);
             for (int i = 0; i < count; i++) {
                 *dstC++ = cache[toggle + fi[i]];
                 toggle = next_dither_toggle(toggle);