bank-payment/account_banking/data/account_banking_data.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
        <!-- Unset readonly state of country_id for ordinary account.
             Leaving it will make it impossible to use bank accounts with
             addresses outside the companies country.
             Ratio: one can have bank accounts in foreign banks. Foreign
             addresses not automatically involve international banking.
        -->
        <record id="base.bank_normal_field_contry" model="res.partner.bank.type.field">
            <field name="name">country_id</field>
            <field name="bank_type_id" ref="base.bank_normal"/>
            <field eval="False" name="required"/>
            <field eval="False" name="readonly"/>
        </record>
    </data>
</openerp>