Fix qmk flash on FreeBSD (#12085)

When the USB device is connected, FreeBSD creates not one, but three
device nodes in /dev, e.g.: /dev/ttyU0, /dev/ttyU0.init, and
/dev/ttyU0.lock.

As a result, this leads to the USB variable containing 3 paths
(and therefore, whitespace) and messages like this one:

    Device /dev/ttyU0
    /dev/ttyU0.init
    /dev/ttyU0.lock has appeared; assuming it is the controller.

This changes fixes the use of the -z flag of "[" (see test(1)). Also, it
removes undesired paths from the USB variable, leaving only
one path there (i.e., "/dev/ttyU0").

0 files changed, 0 insertions, 0 deletions