[FIX] mrp: wizard

Removes unnecessary separator and newline which prevent the product
quantity to be displayed.

opw-658281

addons/mrp/wizard/change_production_qty_view.xml

@@ -10,8 +10,6 @@
             <field name="arch" type="xml">
                 <form string="Change Product Qty">
                     <group>
-                        <separator string="Change Quantity" colspan="4"/>
-                        <newline/>
                         <field name="product_qty"/>
                     </group>
                     <footer>