RawImageDataU16::scaleValues_SSE2(): avoid touching padding

Now, this is indeed a breaking change, and now up to 7 last columnts
may end up being unscaled. This is not good, but we also can't really
touch that padding, asan complains. Perhaps there needs to be two types
of padding.

src/librawspeed/common/RawImageDataU16.cpp

@@ -213,7 +213,6 @@ void RawImageDataU16::scaleValues_SSE2(int start_y, int end_y) {
 
   assert(sub_mul != nullptr);
 
-  uint32_t gw = pitch / 16;
   // 10 bit fraction
   uint32_t mul = static_cast<int>(
       1024.0F * 65535.0F /
@@ -280,7 +279,8 @@ void RawImageDataU16::scaleValues_SSE2(int start_y, int end_y) {
       ssescale = _mm_load_si128(reinterpret_cast<__m128i*>(&sub_mul[12]));
     }
 
-    for (uint32_t x = 0; x < gw; x++) {
+    for (int x = 0; x < static_cast<int>(roundDown(uncropped_dim.x, 8));
+         x += 8) {
       __m128i pix_high;
       __m128i temp;
       _mm_prefetch(reinterpret_cast<char*>(pixel + 1), _MM_HINT_T0);