Allow users to symbolically specify L3 events for Family 17h processors
using the existing AMD Uncore driver.

Source of events descriptions are from section 2.1.15.4.1 "L3 Cache PMC
Events" of the latest Family 17h PPR, available here:

  https://www.amd.com/system/files/TechDocs/55570-B1_PUB.zip

Opnly BriefDescriptions added, since they show with and without
the -v and --details flags.

Tested with:

 # perf stat -e l3_request_g1.caching_l3_cache_accesses,amd_l3/event=0x01,umask=0x80/,l3_comb_clstr_state.request_miss,amd_l3/event=0x06,umask=0x01/ perf bench mem memcpy -s 4mb -l 100 -f default
...
         7,006,831      l3_request_g1.caching_l3_cache_accesses
         7,006,830      amd_l3/event=0x01,umask=0x80/
           366,530      l3_comb_clstr_state.request_miss
           366,568      amd_l3/event=0x06,umask=0x01/
Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Janakarajan Natarajan <janakarajan.natarajan@amd.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Luke Mujica <lukemujica@google.com>
Cc: Martin Liška <mliska@suse.cz>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20190919204306.12598-1-kim.phillips@amd.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>