CHROMIUM: usb: gadget: f_mtp: Add SuperSpeed support

Add SuperSpeed endpoint and companion descriptors.

BUG=chrome-os-partner:43682
TEST=Smaug enumerates as a SuperSpeed device.

Change-Id: I2bf3125d180fcb07222a5740fa67f3526cf3e95c
Signed-off-by: Hui Fu <hfu@nvidia.com>
Signed-off-by: Henry Lin <henryl@nvidia.com>
Signed-off-by: Mark Kuo <mkuo@nvidia.com>
Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/294950