Staging: comedi: propagate timeout errors in s626.c

This patch for s626.c propagates the errors from the newly introduced
calls to comedi_timeout() as far as possible.

Signed-off-by: Chase Southwood <chase.southwood@yahoo.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>