audio policy: remove obsolete AudioPolicyManager class members

Remove mHasA2dp, mHasUsb and mHasRemoteSubmix members from
AudoPolicyManager. They are not needed any more since
we use device descriptors with additional attributes.

Also remove obsolete limitation on device address
length (MAX_DEVICE_ADDRESS_LEN).

Change-Id: Iffe760a521692a4b50be3f6b935af84afb61bb86