[FIX] sale_stock_ux: compute total reserved quantity
[FIX] sale_stock_ux: compute total reserved quantity

closes ingadhoc/sale#511

X-original-commit: 62c2ab1f93eeefeb500c01c9a34f6cdda0f1f444
Signed-off-by: Nicolas Mac Rouillon <8d34fe7b7c65100e706828a8c0d03426900ffb59@adhoc.com.ar>

ingadhoc/sale,ingadhoc/sale,ingadhoc/sale,ingadhoc/sale