After an USB device sees USB bus reset on the bus, it will reset to
device number 0. Per the EHCI debug port specification, a debug
dongle device may reset to the fixed debug device number of 127 instead.
Thus there is no need to try device numbers from 1 to 126.
Do a sanity-check on a returned debug descriptor as I experienced
some USB flash memory to respond on this request with zero-fill data.
Change-Id: I78d58f3dc049cd8c20c6e2aa3a4207ad7e6a6d33
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/3861
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>