[RILMODEM] prevent ofono crash when sim removed while reading

If SIM card is removed and message of that is received before response to RIL_REQUEST_SIM_IO request is received the core will crash. This patch prevents the driver to call core callback function in case SIM card has been removed.
Signed-off-by: Jarko Poutiainen <Jarko.Poutiainen@oss.tieto.com>