usb: gadget: add infrastructure support for super-speed function suspend

The USB 3.0 specification defines a new 'Function Suspend' feature.
This feature enables the USB host to put inactive composite device
functions in a suspended state even when the device itself is not
suspended. This patch extends the existing framework of USB gadget
to properly support the 'Function Resume' and 'Function Remote Wakeup'
related features.

Signed-off-by: Danny Segal <dsegal@codeaurora.org>
Signed-off-by: Mayank Rana <mrana@codeaurora.org>

[jackp@codeaurora.org: also squashed the following commits
usb: gadget: Fix missing function wakeup notification sending on BAM wakeup
usb: gadget: Fix race condition between function wakeup and bus resume
usb: gadget: Resolve recursive spinlock during remote wakeup
usb: composite: don't print the invalid function wakeup failure messages
dwc3: gadget: Replace polling mechanism to go into U0 state
usb: gadget: f_mbim: Queue notification request upon function resume
USB: composite: Hold spinlock before calling usb_func_wakeup_int() API
usb: gadget: Invalidate interface id upon adding function to config
usb: gadget: Fix bug is queuing req upon function suspend ]

Change-Id: I51713eac557eabc7b465d161377c09d4b6afa152
Signed-off-by: Jack Pham <jackp@codeaurora.org>
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>