This patch adds super-speed support to UVC webcam gadget.

Also in this patch:
	- We add the configurability to pass bInterval, bMaxBurst, mult
	  factors for video streaming endpoint (ISOC IN) through module
	  parameters.

	- We use config_ep_by_speed helper routine to configure video
	  streaming endpoint.
Signed-off-by: Bhupesh Sharma <bhupesh.sharma@st.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>