Consistently use tst_require_root() for root user check in syscalls.

Signed-off-by: Nicolas Joly <njoly@pasteur.fr>
diff --git a/testcases/kernel/syscalls/munlockall/munlockall01.c b/testcases/kernel/syscalls/munlockall/munlockall01.c
index 6a2d17b..91db50a 100644
--- a/testcases/kernel/syscalls/munlockall/munlockall01.c
+++ b/testcases/kernel/syscalls/munlockall/munlockall01.c
@@ -124,16 +124,13 @@
 /* setup() - performs all ONE TIME setup for this test. */
 void setup(void)
 {
+	tst_require_root(NULL);
 
 	tst_sig(NOFORK, DEF_HANDLER, cleanup);
 
 	/*set the expected errnos */
 	TEST_EXP_ENOS(exp_enos);
 
-	if (geteuid() != 0) {
-		tst_brkm(TBROK, NULL, "Test must be tested as root");
-	}
-
 	TEST_PAUSE;
 }