UPSTREAM: usb: dwc3: gadget: ep_queue simplify isoc start condition

To improve reading the code this patch moves the cases to start_isoc or
return the function under one common condition check.

Reviewed-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20220306211251.2281335-2-m.grzeschik@pengutronix.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

(cherry picked from commit 26d27a10)

Bug: 263189538
Change-Id: I60ada6edcc6f1a505f2a3d86fc4a6d8b7d22f089
Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>