Avoid explicit narrowing casts

They had been added back in the day with
0c0c6f27 "INTEGRATION: CWS swwarnings"
(adressing "#i69287# warning-free code"), but don't seem to actually silence any
warnings, at least nowadays.  Better to keep such narrowing casts implicit, so
that tools like Clang's -fsanitize=implicit-integer-truncation can detect cases
at runtime where a too-large value erroneously gets truncated by such a cast.

Change-Id: I3bba6fff034e544cd935c0c4dbc98989052add5e
Reviewed-on: https://gerrit.libreoffice.org/68541
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

sw/source/core/layout/atrfrm.cxx

@@ -1088,10 +1088,10 @@ bool SwFormatCol::PutValue( const uno::Any& rVal, sal_uInt8 nMemberId )
                 for(sal_uInt16 i = 0; i < nCount; i++)
                 {
                     SwColumn aCol;
-                    aCol.SetWishWidth(static_cast<sal_uInt16>(pArray[i].Width) );
-                    nWidthSum = static_cast<sal_uInt16>(nWidthSum + pArray[i].Width);
-                    aCol.SetLeft (static_cast<sal_uInt16>(convertMm100ToTwip(pArray[i].LeftMargin)));
-                    aCol.SetRight(static_cast<sal_uInt16>(convertMm100ToTwip(pArray[i].RightMargin)));
+                    aCol.SetWishWidth(pArray[i].Width );
+                    nWidthSum = nWidthSum + pArray[i].Width;
+                    aCol.SetLeft (convertMm100ToTwip(pArray[i].LeftMargin));
+                    aCol.SetRight(convertMm100ToTwip(pArray[i].RightMargin));
                     m_aColumns.insert(m_aColumns.begin() + i, aCol);
                 }
             bRet = true;