usb: dwc3: ep0: don't use ep0in for transfers

In "usb: dwc3: remove special status request handling in ep0" I simplied
a few things and used the generic API for the status transfers. The bug
I introcuded here is that we queue now requests to dep[1] but we don't
clear that list in the stall+start case.
Actually we don't need to use dep[1] at all. We only did in the past to
talk to the correct endpoint (i.e. in or out). This is now take care of
in a diffent place within the ep0 code. So we could queue the in
transfers to dep[0] and don't use dep[1] at all.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>