fix uncore iMC latency computation
fix uncore iMC latency computation

previously for socket i the latency on memory controller channel i
was measured (also running out of bounds if the number of sockets is
larger than the number of channels).

Change-Id: I5aa248188980f9ad9ae2e5dec3d6e64beaad5fb9

opcm/pcm,opcm/pcm,opcm/pcm,opcm/pcm