Bug 10557: remove unused branch parameter from GetBooksellersWithLateOrders

Bug 10557: remove unused branch parameter from GetBooksellersWithLateOrders

C4::Booksellers::GetBooksellersWithLateOrders has an unused parameter.
The $branch variable is never used in the routine.

Test plan:
Check that no behavior changes on the late orders page.

Signed-off-by: Srdjan <srdjan@catalyst.net.nz>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
I couldn't find any use of the branch parameter apart from
the one corrected by this patch. Also tested late orders,
couldn't find any problems.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>