kselftest/arm64: Fix build warnings for ptrace

A "%s" is missing in ksft_exit_fail_msg(); instead, use the newly
introduced ksft_exit_fail_perror().

Signed-off-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20240830052911.4040970-1-dev.jain@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

Author: Dev Jain

tools/testing/selftests/arm64/abi/ptrace.c

@@ -163,10 +163,10 @@ static void test_hw_debug(pid_t child, int type, const char *type_name)
 static int do_child(void)
 {
 	if (ptrace(PTRACE_TRACEME, -1, NULL, NULL))
-		ksft_exit_fail_msg("PTRACE_TRACEME", strerror(errno));
+		ksft_exit_fail_perror("PTRACE_TRACEME");
 
 	if (raise(SIGSTOP))
-		ksft_exit_fail_msg("raise(SIGSTOP)", strerror(errno));
+		ksft_exit_fail_perror("raise(SIGSTOP)");
 
 	return EXIT_SUCCESS;
 }