kmswebrtcendpoint: remove unneeded constants
kmswebrtcendpoint: remove unneeded constants

Change-Id: I5b5bf5071ee810146f8a85f2edd82b1a70f6b115

TribeMedia/kms-elements,shelsonjava/kms-elements,shelsonjava/kms-elements,shelsonjava/kms-elements,TribeMedia/kms-elements,TribeMedia/kms-elements