Do not initiate SDP for incoming AVDTP connection

There are few instances when remote initiates L2CAP
channel for AVDTP signaling but keeps quite after that,
and later on timeout DUT goes for rest of the signalling
procedure but does sdp prior to the same.Few peer
devices deletes a2dp sink sdp record when there is an
ongoing connection, as a result sdp request fails and
DUT fails to proceed with signalling procedure and
connection setup fails.

This patch makes sure that DUT does not go for redundant
sdp request for AVDTP, provided remote has already
established L2cap connection for the same. SDP is done
explicitly only incase of outgoing AV connection.

This issue is seen with Nokia Es headset.

Change-Id: Id44368687d5b3f97bf0258f8d4ff75f185db23af