[FIX] sale: allow access to parent branch fiscal positions on sale order

Currently, on sale orders, you cannot access parent's fiscal positions
from a branch.

Steps to reproduce
-----------------
* install `sale_management`
* set up a company hierarchy. Let's say we have two companies P and C
  such that C is a branch of P.
* let's say that P has a fiscal position F
* switch to company C
* attempt to set fiscal position F on a sale order

You will see that F does not appear on the list.

opw-3773335

closes odoo/odoo#159386

X-original-commit: fa419e550497b1291930f9fb8215a719de331024
Signed-off-by: Séna Serge Nshimiyimana (sesn) <sesn@odoo.com>

addons/sale/models/sale_order.py

@@ -154,7 +154,7 @@ class SaleOrder(models.Model):
         store=True, readonly=False, precompute=True, check_company=True,
         help="Fiscal positions are used to adapt taxes and accounts for particular customers or sales orders/invoices."
             "The default value comes from the customer.",
-        domain="[('company_id', '=', company_id)]")
+    )
     payment_term_id = fields.Many2one(
         comodel_name='account.payment.term',
         string="Payment Terms",