USB: gadget: Add support to enable streaming mode with required function

Supported different usb functions' has different throughput requirement.
USB controller supports streaming mode feature which enables double
buffering scheme on both IN and OUT endpoint, and reduces number of
NAKs for IN transfer. Hence noticeble throughput is increased with it.
Currently streaming mode is disable with USB controller. As supported
usb functions'like mtp, rndis are required to have higher throughput.
Add support which allows to enable streaming mode with usb controller
in device mode when particular function based composition is being enabled.

CRs-Fixed: 550553
Change-Id: Ibf6f3dc3f3b821647ba9beb15ed735a85c8ed586
Signed-off-by: Mayank Rana <mrana@codeaurora.org>