kselftest/arm64/gcs: Correctly check return value when disabling GCS

[ Upstream commit 740cdaf ]

The return value was not assigned to 'ret', so the check afterwards
does not do anything.

Fixes: 3d37d43 ("kselftest/arm64: Add very basic GCS test program")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: t-8ch

tools/testing/selftests/arm64/gcs/basic-gcs.c

@@ -410,7 +410,7 @@ int main(void)
 	}
 
 	/* One last test: disable GCS, we can do this one time */
-	my_syscall5(__NR_prctl, PR_SET_SHADOW_STACK_STATUS, 0, 0, 0, 0);
+	ret = my_syscall5(__NR_prctl, PR_SET_SHADOW_STACK_STATUS, 0, 0, 0, 0);
 	if (ret != 0)
 		ksft_print_msg("Failed to disable GCS: %d\n", ret);