usb: Assure Get Descriptor request is in separate microframe

usb: Assure Get Descriptor request is in separate microframe

The Kingston DT Ultimate USB 3.0 stick is sensitive to this first
Get Descriptor request and if the request is not in a separate
microframe, the stick refuses to operate. Add slight delay, which
is enough for one microframe to pass on any USB spec revision.

Signed-off-by: Marek Vasut <[email protected]>
Cc: Chin Liang See <[email protected]>
Cc: Dinh Nguyen <[email protected]>
Cc: Hans de Goede <[email protected]>
Cc: Stefan Roese <[email protected]>
Cc: Stephen Warren <[email protected]>