perf top: Replace CTRL+z with 'f' as hotkey for enable/disable events

I.e. 'freeze'/'unfreeze', this is because CTRL+z has a well known
action, i.e. suspend the app, perf needs to follow that convention, that
will be done on a separate patch, tho.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-oedcl6ovohara4koig14ayip@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 8f7c4d4..764f7ca 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -1736,7 +1736,7 @@
 	"t             Zoom into current Thread\n"
 	"V             Verbose (DSO names in callchains, etc)\n"
 	"z             Toggle zeroing of samples\n"
-	"CTRL+z        Enable/Disable events\n"
+	"f             Enable/Disable events\n"
 	"/             Filter symbol by name";
 
 	if (browser == NULL)
@@ -1901,7 +1901,7 @@
 			/* Fall thru */
 		case 'q':
 		case CTRL('c'):
-		case CTRL('z'):
+		case 'f':
 			goto out_free_stack;
 		default:
 			continue;