perf vendor events amd: Remove redundant '['

Remove the redundant '['.

'perf list' output before:

  ex_ret_brn
       [[Retired Branch Instructions]

'perf list' output after:

  ex_ret_brn
       [Retired Branch Instructions]

Fixes: 98c07a8f ("perf vendor events amd: perf PMU events for AMD Family 17h")
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: 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/20190919204306.12598-2-kim.phillips@amd.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/pmu-events/arch/x86/amdfam17h/core.json

@@ -13,7 +13,7 @@
   {
     "EventName": "ex_ret_brn",
     "EventCode": "0xc2",
-    "BriefDescription": "[Retired Branch Instructions.",
+    "BriefDescription": "Retired Branch Instructions.",
     "PublicDescription": "The number of branch instructions retired. This includes all types of architectural control flow changes, including exceptions and interrupts."
   },
   {