[FIX] stock_account: Display variant name in INVENTORY VALUATION report

When clicking on "Inventory valuation" in Stock module, the display name
of the variants didn't appear. So with a product template with several
variants, all the variants had the same name in the inventory valuation.

opw:1879572

addons/stock_account/views/stock_account_views.xml

@@ -73,7 +73,7 @@
             <field name="model">product.product</field>
             <field name="arch" type="xml">
                 <tree>
-                    <field name="name"/>
+                    <field name="display_name"/>
                     <field name="qty_at_date"/>
                     <field name="uom_id" groups="product.group_uom"/>
                     <field name="currency_id" invisible="1"/>