RBF: Successfully updated mount point message is coming if we update the mount entry by passing the nameservice id for which mount entry is not present

Test Steps:

1. Add the mount entry like "hdfs dfsrouteradmin -add /apps hacluster /opt
2. Update the mount entry by giving hacluster2 "hdfs dfsrouteradmin -update /apps *hacluster2* /opt -readonly.

*Actual Result:*

Console message says "Successfully updated mount entry for /apps"

*Expected Result:*

This console message will be confusing and the user will be in a impression that the mount entry is readonly updated. But we have passed the nameservice for which the mount entry is not present.

Console message can be like "There is no entries for the hacluster2 nameservice" so that the user will have proper message on the update command executed.