Add update_repo target to agent Makefile
Add update_repo target to agent Makefile

Running make -C chroma-agent update_repo will result in your
developer repo being updated with a new set of agent RPMs.

Change-Id: I3b2b79a8c95fc5a3c077af5dc33b5be65eeb1925

intel-hpdd/intel-manager-for-lustre,intel-hpdd/intel-manager-for-lustre,intel-hpdd/intel-manager-for-lustre