[FIX] point_of_sale: remove unused field

An "iface_payment_terminal" field was present but never used. We
remove it.

addons/point_of_sale/models/pos_config.py

@@ -122,7 +122,6 @@ class PosConfig(models.Model):
         default=_default_invoice_journal)
     currency_id = fields.Many2one('res.currency', compute='_compute_currency', string="Currency")
     iface_cashdrawer = fields.Boolean(string='Cashdrawer', help="Automatically open the cashdrawer.")
-    iface_payment_terminal = fields.Boolean(string='Payment Terminal', help="Enables Payment Terminal integration.")
     iface_electronic_scale = fields.Boolean(string='Electronic Scale', help="Enables Electronic Scale integration.")
     iface_vkeyboard = fields.Boolean(string='Virtual KeyBoard', help=u"Don’t turn this option on if you take orders on smartphones or tablets. \n Such devices already benefit from a native keyboard.")
     iface_customer_facing_display = fields.Boolean(string='Customer Facing Display', help="Show checkout to customers with a remotely-connected screen.")

addons/point_of_sale/static/src/js/models.js

@@ -277,7 +277,6 @@ exports.PosModel = Backbone.Model.extend({
         loaded: function(self,configs){
             self.config = configs[0];
             self.config.use_proxy = self.config.is_posbox && (
-                                    self.config.iface_payment_terminal ||
                                     self.config.iface_electronic_scale ||
                                     self.config.iface_print_via_proxy  ||
                                     self.config.iface_scan_via_proxy   ||