perf kmem: Fix unused argument build warning

Fix:

 builtin-kmem.c: In function 'parse_caller_opt':
 builtin-kmem.c:690: error: unused parameter 'arg'
 builtin-kmem.c: In function 'parse_alloc_opt':
 builtin-kmem.c:697: error: unused parameter 'arg'

Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
LKML-Reference: <4B20A195.8030106@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/builtin-kmem.c

@@ -687,14 +687,14 @@ static int parse_sort_opt(const struct option *opt __used,
 }
 
 static int parse_caller_opt(const struct option *opt __used,
-			  const char *arg, int unset __used)
+			  const char *arg __used, int unset __used)
 {
 	caller_flag = (alloc_flag + 1);
 	return 0;
 }
 
 static int parse_alloc_opt(const struct option *opt __used,
-			  const char *arg, int unset __used)
+			  const char *arg __used, int unset __used)
 {
 	alloc_flag = (caller_flag + 1);
 	return 0;