UPSTREAM: usb: dwc2: gadget: Corrected interval calculation

UPSTREAM: usb: dwc2: gadget: Corrected interval calculation

Calculate the interval according to the USB 2.0 specification section
9.6.6.

Change-Id: I918faedbaa22d0151d48ed45907baf71f000c831
Tested-by: John Keeping <john@metanate.com>
Signed-off-by: Vardan Mikayelyan <mvardan@synopsys.com>
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Huang, Tao <huangtao@rock-chips.com>
(cherry picked from commit 142bd33fcd185d850178f7f8697ecbeaaa18e257)