[FIX]mrp: change description if there is no workorder
[FIX]mrp: change description if there is no workorder

task-2128553

closes odoo/odoo#42853

Signed-off-by: Simon Lejeune (sle) <1969d8dff896674c2d819e813f5e88ca826229ab@openerp.com>

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo