perf/x86/uncore: add SNB/IVB/HSW client uncore memory controller support

perf/x86/uncore: add SNB/IVB/HSW client uncore memory controller support

This patch adds a new uncore PMU for Intel SNB/IVB/HSW client
CPUs. It adds the Integrated Memory Controller (IMC) PMU. This
new PMU provides a set of events to measure memory bandwidth utilization.

The IMC on those processor is PCI-space based. This patch
exposes a new uncore PMU on those processor: uncore_imc

Two new events are defined:
  - name: data_reads
  - code: 0x1
  - unit: 64 bytes
  - number of full cacheline read requests to the IMC

  - name: data_writes
  - code: 0x2
  - unit: 64 bytes
  - number of full cacheline write requests to the IMC

Documentation available at:
http://software.intel.com/en-us/articles/monitoring-integrated-memory-controller-requests-in-the-2nd-3rd-and-4th-generation-intel

Cc: mingo@elte.hu
Cc: acme@redhat.com
Cc: ak@linux.intel.com
Cc: zheng.z.yan@intel.com
Cc: peterz@infradead.org
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1392132015-14521-7-git-send-email-eranian@google.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>