fix loading of RLE compressed PSD files

decodeRLEData() expects a quint16 as length, but the PSD loader calls it
 with a quint32.
We do need quint32 for PSD, otherwise it would overflow for images
bigger than 256x256 pixels (it's the pixel count there, i.e. width x
 height).

BUG: 354413
FIXED-IN: 5.19.0
REVIEW: 126684

src/imageformats/rle_p.h

@@ -75,7 +75,7 @@ template<typename Item, typename Func1, typename Func2>
 static inline bool decodeRLEData(RLEVariant variant,
                                  QDataStream &stream,
                                  Item *dest,
-                                 quint16 length,
+                                 quint32 length,
                                  Func1 readData,
                                  Func2 updateItem)
 {