libusb: fix host dependency

Since commit 127924094678e459b0d31cd81605317479d80c7f the libusbx is used
instead of the original libusb. The new library depends on libudev by default
and the configure step fails if this library is not present on the host.
Switch off this feature to avoid this new dependency.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>