sweetberry: add usb fw update

Port USB firmware update to stm32f4 dwc usb from st usb.
This includes usb dwc usb stream inplementation, generic
endpoint interfaces, and the sweetberry test case.

BUG=chromium:608039
TEST=usb update works
BRANCH=None

Change-Id: Ia26e4f7e990ee64991468799c99b036f5f32190f
Signed-off-by: Nick Sanders <nsanders@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/377520
Reviewed-by: Randall Spangler <rspangler@chromium.org>
11 files changed