Revert "Fix a bug in SUMSQ"

This reverts commit 793d1aba.

Just discovered that this is wrong, sorry for fuzz.

Change-Id: Id8365f00f615275d3bdd41ab630729e6f19ac577
Reviewed-on: https://gerrit.libreoffice.org/18848Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>

sc/source/core/tool/interpr6.cxx

@@ -408,7 +408,6 @@ void IterateMatrix(
         case ifSUMSQ:
         {
             ScMatrix::IterateResult aRes = pMat->SumSquare(bTextAsZero);
-            fRes = aRes.mfFirst;
             fRes += aRes.mfRest;
             rCount += aRes.mnCount;
         }