Removed all occurences of RTL_CONSTASCII_USTRINGPARAM in chart2.

Change-Id: I0ab188e2d67a5fc17a3653e5213031f6e2c2581d
Reviewed-on: https://gerrit.libreoffice.org/2244Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Michael Stahl <mstahl@redhat.com>