Revert "BUG-634: Rework KeyAccess to work on maps"

This reverts commit 66785488a640210e8ec58a75d6edeeadfde35a9c.

Conflicts:
	tcp-md5/nio/src/main/java/org/opendaylight/bgpcep/tcpmd5/nio/MD5ChannelOptions.java

Change-Id: I88a8272b50cddc41314ed8c88dfb919da008a053
Signed-off-by: Robert Varga <rovarga@cisco.com>