NFC: unassigned variable pNewItem is always nullptr

In 2015 commit 2ebd79b3 a
possible initialization of the variable was removed. So
at this point pNewItem must return false.

Change-Id: I5af9d8440463c96323c38a01f255c1dbb0113e09
Reviewed-on: https://gerrit.libreoffice.org/54395Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Justin Luth <justin_luth@sil.org>

svl/source/items/itemprop.cxx

@@ -218,7 +218,7 @@ void SfxItemPropertySet::setPropertyValue( const SfxItemPropertySimpleEntry& rEn
     SfxItemState eState = rSet.GetItemState( rEntry.nWID, true, &pItem );
     if (SfxItemState::SET != eState && SfxItemPool::IsWhich(rEntry.nWID))
         pItem = &rSet.GetPool()->GetDefaultItem(rEntry.nWID);
-    if(!pNewItem && pItem)
+    if (pItem)
     {
         pNewItem.reset(pItem->Clone());
     }