selftests/sigaltstack: Fix wrong format specifier

Compiling sigaltstack selftest after adding a __printf() attribute to
ksft_print_msg() exposes -Wformat warning in main().
The format specifier inside ksft_print_msg() expects a long
unsigned int but the passed variable is of unsigned int type.

Fix the format specifier so it matches the passed 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/sigaltstack/sas.c

@@ -111,7 +111,7 @@ int main(void)
 
 	/* Make sure more than the required minimum. */
 	stack_size = getauxval(AT_MINSIGSTKSZ) + SIGSTKSZ;
-	ksft_print_msg("[NOTE]\tthe stack size is %lu\n", stack_size);
+	ksft_print_msg("[NOTE]\tthe stack size is %u\n", stack_size);
 
 	ksft_print_header();
 	ksft_set_plan(3);