usb: dwc3: gadget: always use frame number from XferNotReady

The core requires the extra two bits of information for properly
scheduling Isochronous transfers. This means that we can't rely on
__dwc3_gadget_get_frame(). Let's always cache uFrame number from
XferNotReady instead.

Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Git-commit: 5828cada99086c41cf23c4d4b63090b23c473008
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


[hemantk@codeaurora.org: resolved merge conflict]
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
Change-Id: I4417a8201689902bd55e4f98e6b02f66bf571fbb