USB: cp210x: Add 81E8 (Zephyr Bioharness)

As reported in
http://bugzilla.kernel.org/show_bug.cgi?id=10980



Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>