[FIX] payment: fees computation depending on country

The computed fees can depend on the country.
There was a typo about it:
there is no `country_id` field on the `payment.transaction` model,
it's `partner_country_id`.

Therefore, the computed fees according to the country
were not always correctly computed.

e.g. for Paypal, where the domestic fees
are lower than the international fees, it always
computed the fees as international.

opw-651778

addons/payment/models/payment_acquirer.py

@@ -448,7 +448,7 @@ class PaymentTransaction(osv.Model):
             custom_method_name = '%s_compute_fees' % acquirer.provider
             if hasattr(Acquirer, custom_method_name):
                 fees = getattr(Acquirer, custom_method_name)(
-                    cr, uid, acquirer.id, values.get('amount', 0.0), values.get('currency_id'), values.get('country_id'), context=None)
+                    cr, uid, acquirer.id, values.get('amount', 0.0), values.get('currency_id'), values.get('partner_country_id'), context=None)
                 values['fees'] = float_round(fees, 2)
 
             # custom create