[FIX] l10n_gcc_pos: fix country undefined

When the country is not defined on the company, there was an error when using the gcc l10n.
To fix this, we check if the country is set before going further.

closes odoo/odoo#109178

X-original-commit: 9c8dec30
Signed-off-by: Trinh Jacky (trj) <trj@odoo.com>
Signed-off-by: Heinz Robin (rhe) <rhe@odoo.com>