I Could resolve it by checking already installed plugins at where it was giving me this error. I just uninstalled all the plugins which had conflicting dependency and try to install the updates. It worked well.!
check the marked area in this linked image
Generally, why it should happen is that while updating plugins lately,they have evolved 2-3 updates and during which plugins have introduced some new functions that have to be installed and also are to be updated. This thing creates conflicts of dependency. Eclipse tries to update which is not already existing/installed and it also tells install it first which creates conflicts.
So, when you uninstall the plugins, now it installs the latest plugins rather then updating. it means you updating eclipse plugins manually(by uninstalling older and installing latest). This may happen if you have skipped 2-3 updates and now looking for latest update.