Remove case EVENT_TYPE_AT_CHLD from connecting state

AT+CHLD=? will be hanlded by stack directly, HeadsetStateMachine
shouldn't reveice any AT+CHLD event during connecting.

Bug: 112681866
Test: 1. runtest bluetooth
      2. make MO/MT call and VOIP call
Change-Id: I476ef9240d8a5256b3c6307f758e7de7be4afd0b
1 file changed