USB: keyspan: fix overrun-error reporting

Fix reporting of overrun errors, which are not associated with a
character. Instead insert a null character and report only once.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
1 file changed