usb: gadget: f_qdss: Remove queuing of ZLP

Currently qdss driver queues ZLP after request completion which is already
being taken care in gadget driver. This leads to SMMU fault when SW path
is enabled for qdss using sg list. This change removes queuing of ZLP from
qdss function driver.

Change-Id: Ib5e5fad9f37f8dc7e09984668872b4408a783b53
Signed-off-by: Pratham Pratap <prathampratap@codeaurora.org>