Fixed CSI-MeasConfig configuration under ServingCellConfig to be optional.
3GPP 38.331 states:
csi-MeasConfig SetupRelease { CSI-MeasConfig }
This means that at release procedure, this parameter is not set. Change
Protobuf structure to 'oneof' to support optionality for csi-MeasConfig.
Signed-off-by: Timo Tietavainen <timo.tietavainen@nokia.com>
Change-Id: Id208577f3a3042ccee7b744277ed2dac89eac45b