[FIX] product: product price assumed currency
[FIX] product: product price assumed currency

When a product has no company set, it assumed it use the main company
currency. Read the main company currency as SUPERUSER as current user
may not have access to it.

Followup of 3622c0d12a879d8184b249c49ba2e24995d6a595.

storm-computers/odoo,sysadminmatmoz/OCB,storm-computers/odoo,stephen144/odoo,ygol/odoo,laslabs/odoo,stephen144/odoo,sysadminmatmoz/OCB,hip-odoo/odoo,hip-odoo/odoo,microcom/odoo,laslabs/odoo,bplancher/odoo,hip-odoo/odoo,Elico-Corp/odoo_OCB,stephen144/odoo,sysadminmatmoz/OCB,Elico-Corp/odoo_OCB,storm-computers/odoo,hip-odoo/odoo,Elico-Corp/odoo_OCB,dfang/odoo,storm-computers/odoo,microcom/odoo,ygol/odoo,stephen144/odoo,dfang/odoo,dfang/odoo,laslabs/odoo,microcom/odoo,dfang/odoo,ygol/odoo,dfang/odoo,hip-odoo/odoo,ygol/odoo,stephen144/odoo,laslabs/odoo,storm-computers/odoo,Elico-Corp/odoo_OCB,dfang/odoo,laslabs/odoo,bplancher/odoo,ygol/odoo,bplancher/odoo,microcom/odoo,Elico-Corp/odoo_OCB,stephen144/odoo,sysadminmatmoz/OCB,bplancher/odoo,laslabs/odoo,microcom/odoo,ygol/odoo,sysadminmatmoz/OCB,bplancher/odoo,storm-computers/odoo,ygol/odoo,sysadminmatmoz/OCB,sysadminmatmoz/OCB,hip-odoo/odoo,Elico-Corp/odoo_OCB,bplancher/odoo,microcom/odoo