mount/mount05.c: Add mode argument to open call.

This patch fixes this build error on Ubuntu introduced with commit
9146d83d410dc060124344fcbcdbf46280b674a2.

In file included from /usr/include/fcntl.h:279:0,
                 from mount05.c:31:
In function ‘open’,
    inlined from ‘main’ at mount05.c:94:12:
/usr/include/x86_64-linux-gnu/bits/fcntl2.h:50:24: error: call to ‘__open_missing_mode’ declared with attribute error: open with O_CREAT in second argument needs 3 arguments

Signed-off-by: Vinson Lee <vlee@twitter.com>
Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
diff --git a/testcases/kernel/syscalls/mount/mount05.c b/testcases/kernel/syscalls/mount/mount05.c
index 8a78938..65cc0ab 100644
--- a/testcases/kernel/syscalls/mount/mount05.c
+++ b/testcases/kernel/syscalls/mount/mount05.c
@@ -91,7 +91,7 @@
 			tst_resm(TFAIL | TTERRNO, "mount(2) failed");
 		} else {
 
-			if (open(file_des, O_CREAT | O_EXCL) == -1 &&
+			if (open(file_des, O_CREAT | O_EXCL, S_IRWXU) == -1 &&
 			    errno == EEXIST)
 				tst_resm(TPASS, "bind mount is ok");
 			else