perf/x86/intel/uncore: Add Broadwell-U uncore IMC PMU support

perf/x86/intel/uncore: Add Broadwell-U uncore IMC PMU support

This patch enables the uncore Memory Controller (IMC) PMU
support for Intel Broadwell-U (Model 61) mobile processors.
The IMC PMU enables measuring memory bandwidth.

To use with perf:
$ perf stat -a -I 1000 -e
uncore_imc/data_reads/,uncore_imc/data_writes/ sleep 10

Tested-by: Sonny Rao <sonnyrao@chromium.org>
Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kan.liang@intel.com
Cc: peterz@infradead.org
Link: http://lkml.kernel.org/r/20150423065642.GA4890@thinkpad
Signed-off-by: Ingo Molnar <mingo@kernel.org>