tomoyo: fix sparse warning

Fix sparse warning.

$ make C=2 SUBDIRS=security/tomoyo CF="-D__cold__="
 CHECK   security/tomoyo/common.c
 CHECK   security/tomoyo/realpath.c
 CHECK   security/tomoyo/tomoyo.c
security/tomoyo/tomoyo.c:110:8: warning: symbol 'buf' shadows an earlier one
security/tomoyo/tomoyo.c:100:7: originally declared here

Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp>
Signed-off-by: James Morris <jmorris@namei.org>

security/tomoyo/tomoyo.c

@@ -107,13 +107,13 @@ static char *tomoyo_sysctl_path(struct ctl_table *table)
 	*--end = '\0';
 	buflen--;
 	while (table) {
-		char buf[32];
+		char num[32];
 		const char *sp = table->procname;
 
 		if (!sp) {
-			memset(buf, 0, sizeof(buf));
-			snprintf(buf, sizeof(buf) - 1, "=%d=", table->ctl_name);
-			sp = buf;
+			memset(num, 0, sizeof(num));
+			snprintf(num, sizeof(num) - 1, "=%d=", table->ctl_name);
+			sp = num;
 		}
 		if (tomoyo_prepend(&end, &buflen, sp) ||
 		    tomoyo_prepend(&end, &buflen, "/"))