perf pmu: Support per pmu json aliases

perf pmu: Support per pmu json aliases

Add support for registering json aliases per PMU. Any alias with an unit
matching the prefix is registered to the PMU.  Uncore has multiple
instances of most units, so all these aliases get registered for each
individual PMU (this is important later to run the event on every
instance of the PMU).

To avoid printing the events multiple times in perf list filter out
duplicated events during printing.

v2: Rely on uncore_ prefix already in unit
v3: Document why calls were reordered

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20170128020345.19007-4-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>