You can do it using recursive CTE, supported since version 2.1, something like
WITH RECURSIVE tQty AS(
SELECT ta.name, ta.qty
FROM T ta
WHERE(ta.qty > 0)
UNION ALL
SELECT tb.name, tb.qty-1
FROM tQty tb
WHERE(tb.qty-1 > 0)
)
SELECT name,qty FROM tQty
ORDER BY name