usb: gadget: s3c-hsotg: fix "protocol stall" handling

After normal handling of SetupDone interrupt, XferCompl interrupt occurs, and
then we enqueue new setup request. But when ep0 is stalled, there is no
XferCompl, so we have to enqueue setup request immediately after stalling ep.
Otherwise incoming control requests won't be processed correctly.

Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>