Staging: ipack/devices/ipoctal: remove error_flag field from ipoctal struct.

Remove the error_flag field from the ipoctal structure, as the error code
is handled through the tty abstraction. Remove the values definition as well.

Signed-off-by: Miguel Gómez <magomez@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>