tools/usb: remove unneeded 'continue' and simplify condition

Basically remove unneeded code. Since that 'continue' is at the end
of the for() there's no need for it.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>