usb: dwc3: gadget: Fix setting of DEPCFG.bInterval_m1

Valid range for DEPCFG.bInterval_m1 is from 0 to 13, and it must be set
to 0 when the controller operates in full-speed. See the programming
guide for DEPCFG command section 3.2.2.1 (v3.30a).

Fixes: 72246da4

 ("usb: Introduce DesignWare USB3 DRD Driver")
Cc: <stable@vger.kernel.org>
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/3f57026f993c0ce71498dbb06e49b3a47c4d0265.1612820995.git.Thinh.Nguyen@synopsys.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>