usb: dwc3: gadget: Ignore Packet Pending bit

Currently the controller handles single stream only. So, Ignore Packet
Pending bit for stream selection and don't search for another stream if
the host sends Data Packet with PP=0 (for OUT direction) or ACK with
NumP=0 and PP=0 (for IN direction). This slightly improves the stream
performance.

Acked-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/097ba9e104c143f7ba0195ebff29390ec3043692.1618282705.git.Thinh.Nguyen@synopsys.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>