Add r-w property of emergency number list.

Currently, the emergency calls are put into an readonly property ro.ril.ecclist.

It is possible that ecclist has to be changed before and after SIM pin lock.

And ecclist can also be changed after network broadcasts the local emgergency numbers.

So add r-w property ril.ecclist to make emergency number list changable, while still

check r-o property to make old RIL work.