libpayload: Add UNKNOWN_SPEED to usb_speed enum

xhci_rh_port_speed return -1 if the port is disabled. The usb_speed enum
is unsigned so this results in a positive value which implies success.

Adding a -1 to the enum will make it signed so the >= 0 check will work

TEST=verified on grunt that -1 is returned when port is disabled.

Change-Id: I98a373717d52dfb6ca4dcc53a00dc1b4c240a919
Signed-off-by: Raul E Rangel <>
Tested-by: build bot (Jenkins) <>
Reviewed-by: Julius Werner <>
2 files changed