fix wrong read size in ToColor_S4444_Opaque

- S4444 takes 16bits, not 32bits
- This caused sporadic failure in CTS BitmapFactoryTest#testDecodeStream4

Bug: 7179389
Change-Id: Ib36a3a569b3149d74f36ae67a069a7b65a72e895

Author: Keun young Park

core/jni/android/graphics/Bitmap.cpp

@@ -145,7 +145,7 @@ static void ToColor_S4444_Alpha(SkColor dst[], const void* src, int width,
 static void ToColor_S4444_Opaque(SkColor dst[], const void* src, int width,
                                  SkColorTable*) {
     SkASSERT(width > 0);
-    const SkPMColor* s = (const SkPMColor*)src;
+    const SkPMColor16* s = (const SkPMColor16*)src;
     do {
         SkPMColor c = SkPixel4444ToPixel32(*s++);
         *dst++ = SkColorSetRGB(SkGetPackedR32(c), SkGetPackedG32(c),