COMP: missing cast when calling gdcm::DataElement::SetByteValue

Second arguments need to be cast into uint32_t in order to be implicity
converted to gdcm::VL

Change-Id: I0c08d3f94eea88be7fbd2a5fbd633a0688197de6
Merge topic 'GDCMIOCastIssue_release'

17c91c6e COMP: missing cast when calling gdcm::DataElement::SetByteValue