utils: introduce find_usbdebug.sh to help find USB debug ports

utils: introduce find_usbdebug.sh to help find USB debug ports

Carl-Daniel made this script a long time ago but it never was picked up
in the tree. Now that USB debugging is way more common it makes
sense to include it.

I have made a number of changes to the original version:
* -h help text
* check for running as root
* enhanced readability (test -> if)
* new execution flow and refined output that better shows the device(s)
  attached to the debug port(s)
* handling of Intel rate-matching hubs
* hiding of (bogus) error messages from lspci and lsusb

Signed-off-by: Stefan Tauner <stefan.tauner@gmx.at>
Change-Id: Iadf775e990f5c5f91a28d57e3331d1f59acee305
Reviewed-on: https://review.coreboot.org/c/9305
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>