USB: c67x00-ll-hpi.c: signedness bug in ll_recv_msg()

The callers expect this function to return zero on success or -EIO if it
times out.  The type should be int instead of unsigned short.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>