Wrong since

    commit 597f7b1f
    Date:   Sun Nov 20 02:21:56 2016 +0100

        tdf#48140 Replace uno call from worksheethelper.cxx

We are importing a document, so asserting on our own max
dimensions is wrong.

Wrong is also to compare positions <= MAXCOLCOUNT or
<= MAXROWCOUNT, if at at all it should had been <= MAXCOL and
<= MAXROW

Change-Id: I9f3aae061785ab62de7c709e19fc68653f15ed1e
Reviewed-on: https://gerrit.libreoffice.org/50397Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Jenkins <ci@libreoffice.org>