[GRIL] use glib to split string to array

Signed-off-by: Jarko Poutiainen <Jarko.Poutiainen@oss.tieto.com>
[RILMODEM] use glib to split string to array and some style fixes

Signed-off-by: Jarko Poutiainen <Jarko.Poutiainen@oss.tieto.com>