Allow AVDTP SetConfig from INIT state

This addresses AVDTP codec reconfiguration issue on the A2DP Sink side.
Apparently, the A2DP Sink rejects AVDTP Reconfig - then, after the AVDTP Close
(normal), the Sink side doesn't accept AVDTP SetConfig anymore.
If the codecs are already known to the A2DP SRC, it doesn't need the
AVDTP Discover mechanism just for the purpose of the codec reconfiguration.
Hence, we can allow SetConfig from INIT state.

Bug: 115894702
Test: Manual with switching the AAC Sample Rate in the Develop Options
Change-Id: I3b1603dc6ef344eea50383df2eddf309dec80a28