usb: dwc3: gadget: Fix starting microframe for ISOC

The gadget wants to set the starting microframe for the first ISOC TRB
to 4 microframes in the future, but it does so by multiplying the
dep->interval. This only works if dep->interval = 1. For other intervals
it will put it 4 *intervals* in the future which may be way too much.

Fix so that it always adds just one interval or at least 4 microframes.

Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Git-commit: af771d731b8e31e6c5aced2b1b066edd16106a6f
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>
Change-Id: I3567f3a1b4160ac0069642873880e61fdc2c800e