Fix bug when serializing INT32 constant data

Signed-off-by: Kevin Cheng <kevin.cheng@arm.com>
Change-Id: I5321aedb5766dd1b38fa8251ffb84fa880d4ecd5
diff --git a/python/tosa_serializer.py b/python/tosa_serializer.py
index b1c5dae..04b2fc4 100644
--- a/python/tosa_serializer.py
+++ b/python/tosa_serializer.py
@@ -414,7 +414,7 @@
                     b0 = val_u32 & ByteMask
                     b1 = (val_u32 >> np.uint32(8)) & ByteMask
                     b2 = (val_u32 >> np.uint32(16)) & ByteMask
-                    b3 = (val_u32 >> np.uint32(32)) & ByteMask
+                    b3 = (val_u32 >> np.uint32(24)) & ByteMask
                     u8_data.extend([b0, b1, b2, b3])
             elif self.dtype == DType.INT48:
                 for val in self.data: