selftests/openat2: Fix wrong format specifier

Compiling openat2 selftest after adding a __printf() attribute to
ksft_print_msg() exposes a -Wformat warning in test_openat2_flags().
The wrong format specifier is used for printing test.how->flags
variable.

Change the format specifier to %llX so it matches the printed variable.
Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/openat2/openat2_test.c

@@ -300,7 +300,7 @@ void test_openat2_flags(void)
 
 			ksft_print_msg("openat2 unexpectedly returned ");
 			if (fdpath)
-				ksft_print_msg("%d['%s'] with %X (!= %X)\n",
+				ksft_print_msg("%d['%s'] with %X (!= %llX)\n",
 					       fd, fdpath, fdflags,
 					       test->how.flags);
 			else