fix compilation error in cluster helper
fix compilation error in cluster helper

added desc field to Cluster type to fix
the compilation error.

Signed-off-by: Kanagaraj M <a744b691cd98174fb19a473a8cf78b810491e452@redhat.com>

Tendrl/dashboard,cloudbehl/tendrl_frontend,cloudbehl/tendrl_frontend,skyrings/kitoon,Tendrl/dashboard,skyrings/kitoon,kmkanagaraj/usm-client-2,kmkanagaraj/usm-client-2,skyrings/kitoon,kmkanagaraj/usm-client-2