[FIX] mrp: useless size for field code on mrp.bom

The size of 16 characters for the field size on mrp.bom
is useless.

opw:684441

addons/mrp/mrp.py

@@ -150,7 +150,7 @@ class mrp_bom(osv.osv):
     _inherit = ['mail.thread']
 
     _columns = {
-        'code': fields.char('Reference', size=16),
+        'code': fields.char('Reference'),
         'active': fields.boolean('Active', help="If the active field is set to False, it will allow you to hide the bills of material without removing it."),
         'type': fields.selection([('normal','Manufacture this product'),('phantom','Ship this product as a set of components (kit)')], 'BoM Type', required=True,
                 help= "Set: When processing a sales order for this product, the delivery order will contain the raw materials, instead of the finished product."),