Telephony: Reset the duration after the call is accepted

In android original design, the duration of CDMA MO call is started from
the dial command sent, so it is not the real duration of the active time.
In this patch, a new message is registered to listen the event of the call
accepted, and reset the duration when the event happens.

Change-Id: Ibb4de7c9eed45bd3183722b67854374182c5ef43