[FIX] product: variant name_get for specific providers
[FIX] product: variant name_get for specific providers

This is related to revision
b65c67a2598fd3ad433af05ed49d398c473b76ae

The field `seller_ids` is a field which is set
on the `product.template`, and this is why
the condition `(x.product_id == product)` is being applied
in the list comprehension searching the current seller
of the product sellers.

The `variant` variable is a string containing
the attribute name of a variant.
Therefore, if a product tempalte has only one variant, without
any attribute (e.g. when you don't use variants),
`variant` will be empty, and therefore the condition
`if variant:` will be `False`, and therefore it won't search
in the product sellers with a specific `product.product`, while it
should, as, even if there are no attributes, there could be a
seller line with this specific `product.product`.

Besides, as we are in the `name_get` of `product.product`, and
not the `name_get` of `product.template`, we are always in the case
of a `variant`, this test is therefore pointless.

opw-682390

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