audit: replace magic audit syscall class numbers with macros

Replace audit syscall class magic numbers with macros.

This required putting the macros into new header file
include/linux/audit_arch.h since the syscall macros were
included for both 64 bit and 32 bit in any compat code, causing
redefinition warnings.

Link: https://lore.kernel.org/r/2300b1083a32aade7ae7efb95826e8f3f260b1df.1621363275.git.rgb@redhat.com
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
[PM: renamed header to audit_arch.h after consulting with Richard]
Signed-off-by: Paul Moore <paul@paul-moore.com>

include/linux/audit_arch.h

@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* audit_arch.h -- Arch layer specific support for audit
+ *
+ * Copyright 2021 Red Hat Inc., Durham, North Carolina.
+ * All Rights Reserved.
+ *
+ * Author: Richard Guy Briggs <rgb@redhat.com>
+ */
+#ifndef _LINUX_AUDIT_ARCH_H_
+#define _LINUX_AUDIT_ARCH_H_
+
+enum auditsc_class_t {
+	AUDITSC_NATIVE = 0,
+	AUDITSC_COMPAT,
+	AUDITSC_OPEN,
+	AUDITSC_OPENAT,
+	AUDITSC_SOCKETCALL,
+	AUDITSC_EXECVE,
+
+	AUDITSC_NVALS /* count */
+};
+
+#endif