Remove wrong concatenation of text from EditView in SmXMLImport::endDocument, and use
just the text extracted from formula.

After the SmXMLImport::endDocument method, we compare the text from doc(extracted from formula) and
from editview(text inserted before call the importer) and as they're different, the text from
formula will be inserted in the current edit cursor position.

Also, remove bogus pDocShell->SetText( String() ), as we will set the text some lines below.

Change-Id: Ia317a23d27964a9d1264dcaf9ec0d38b8c586655
Reviewed-on: https://gerrit.libreoffice.org/4369Reviewed-by: Noel Power <noel.power@suse.com>
Tested-by: Noel Power <noel.power@suse.com>