The only place this function is called (SvxMSDffManager::ImportGraphic,
filter/source/msfilter/msdffimp.cxx) it is passed the sal_uInt32 return value
from a call to DffPropSet::GetPropertyValue, so that seems a better type.
(SvxMSDffManager::ImportOLE used long at least since
d2000efb "#i106421#: move msfilter to filter";
DffPropSet::GetPropertyValue used UINT32 back then, changed to sal_uInt32 with
e8c2c1da "removetooltypes01: #i112600# remove
tooltypes from filter".  Unclear if those had ever had more compatible types in
the distant past.)

Change-Id: Ia486d169cd2cc0e73042e72fd4476cc2ae0e8cc5