I have upgrade the SEPM in 12.1 RU5. After upgradation i have go to Install Packages in console to find the avaialble packages.
There i have not found the linux packages. I have only seen the window and mac packages.
In the article chetan mention that "LinuxRPM & LinuxDPKG packages have been added under admin --> Install Packages"
https://www-secure.symantec.com/connect/articles/whats-new-sepm-121-ru5-user-interface-differences
Please do the needful.