Show the correct footprint name on footprint filter mismatch ERC warning.

The lower case variant used for internal comparison was being used which
is confusing because it doesn't match the footprint name capitalization.

(cherry picked from commit a9cea9fbb7)

eeschema/erc/erc.cpp

@@ -1633,7 +1633,7 @@ int ERC_TESTER::TestFootprintFilters()
             {
                 std::shared_ptr<ERC_ITEM> ercItem = ERC_ITEM::Create( ERCE_FOOTPRINT_LINK_ISSUES );
                 msg.Printf( _( "Assigned footprint (%s) doesn't match footprint filters (%s)." ),
-                            lowerItemName,
+                            footprint.GetUniStringLibItemName(),
                             wxJoin( filters, ' ' ) );
                 ercItem->SetErrorMessage( msg );
                 ercItem->SetItems( sch_symbol );