fdo#71810 make argument names consistent with Gnumeric and Excel

Using "Number" as name for both argument 1 and 2 can be confusing, too.

Change-Id: I9fcc7cdfd32b0549a8df9d32c03f4207c040401c
Reviewed-on: https://gerrit.libreoffice.org/7408
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>