Add support for DSDA.

Add support for below.
1) Maintain LCH & Active subscriptions and inform changes to
lower layers.
2) LCHR and SCH tones
3) Allow calls on other sub, when call is already active
in the current sub.

MSIM(DSDA): Check subscription of other active calls

For updating add call capability to a call, check if any other
active call is there in same subscription or not. if other call
is in same subscription, only then disable add call capability as
maximum of 2 active calls are supported per subscription.

Conflicts:
	src/com/android/server/telecom/Call.java

Change-Id: Id6c774496266afbda61c0ab10610221fab3daa47