usb: dwc3: add tracepoints to aid debugging

When we're debugging hard-to-reproduce and time-sensitive
use cases, printk() poses too much overhead. That's when
the kernel's tracing infrastructure comes into play.

This patch implements a few initial tracepoints for the
dwc3 driver. More traces can be added as necessary in order
to ease the task of debugging dwc3.

Reviewed-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

diff --cc drivers/usb/dwc3/Makefile
Simple merge

diff --cc drivers/usb/dwc3/core.h
Simple merge

diff --cc drivers/usb/dwc3/debug.c
Simple merge

diff --cc drivers/usb/dwc3/debug.h
Simple merge

diff --cc drivers/usb/dwc3/ep0.c
Simple merge

diff --cc drivers/usb/dwc3/gadget.c
Simple merge

diff --cc drivers/usb/dwc3/io.h
Simple merge

diff --cc drivers/usb/dwc3/trace.c
Simple merge

diff --cc drivers/usb/dwc3/trace.h
Simple merge