perf kmem: Perform some cleanup if '--time' is given an invalid value

If the string passed in '--time' is invalid, we must do some cleanup
before leaving. As in the other error handling paths of this function.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel-janitors@vger.kernel.org
Fixes: 2a865bd8dddd ("perf kmem: Add option to specify time window of interest")
Link: http://lkml.kernel.org/r/20170916060936.28199-1-christophe.jaillet@wanadoo.fr
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-kmem.c

@@ -1983,7 +1983,8 @@ int cmd_kmem(int argc, const char **argv)
 
 	if (perf_time__parse_str(&ptime, time_str) != 0) {
 		pr_err("Invalid time string\n");
-		return -EINVAL;
+		ret = -EINVAL;
+		goto out_delete;
 	}
 
 	if (!strcmp(argv[0], "stat")) {