Felipe writes:

usb: changes for v4.16 merge window

Not many changes here, the most important being an improvement for TI's
AM57xx and DRA7xx devices which allows them to disable a metastability
workaround in situations where we know what's going on.

Other than that, we have a set of changes on Renesas UDC to make the
code a little easier to read and maintain while also better supporting
extcon framework.

The u_serial adaptation layer learned to use kfifo instead of cooking
its own FIFO implementation.

DWC3 learned to decode a few more USB requests on the trace output.