add index in getPixels for F16

src/core/SkLinearBitmapPipeline_sample.h

Index: src/core/SkLinearBitmapPipeline_sample.h
diff --git a/src/core/SkLinearBitmapPipeline_sample.h b/src/core/SkLinearBitmapPipeline_sample.h
index d436e393996db035a77344e0d8fb4da0ce175abd..539ce006156e6714d46e78159b37c5d731e6dc42 100644
--- a/src/core/SkLinearBitmapPipeline_sample.h
+++ b/src/core/SkLinearBitmapPipeline_sample.h
@@ -777,7 +777,7 @@ public:
     }
 
     Sk4f getPixelAt(const void* vsrc, int index) {
-        const uint64_t* src = static_cast<const uint64_t*>(vsrc);
+        const uint64_t* src = static_cast<const uint64_t*>(vsrc) + index;
         return SkHalfToFloat_01(*src);
     }