feat(mpmm): add support for MPMM

MPMM - the Maximum Power Mitigation Mechanism - is an optional
microarchitectural feature present on some Armv9-A cores, introduced
with the Cortex-X2, Cortex-A710 and Cortex-A510 cores.

MPMM allows the SoC firmware to detect and limit high activity events
to assist in SoC processor power domain dynamic power budgeting and
limit the triggering of whole-rail (i.e. clock chopping) responses to
overcurrent conditions.

This feature is enabled via the `ENABLE_MPMM` build option.
Configuration can be done via FCONF by enabling `ENABLE_MPMM_FCONF`, or
by via the plaform-implemented `plat_mpmm_topology` function.

Change-Id: I77da82808ad4744ece8263f0bf215c5a091c3167
Signed-off-by: Chris Kay <chris.kay@arm.com>
diff --git a/include/lib/fconf/fconf_mpmm_getter.h b/include/lib/fconf/fconf_mpmm_getter.h
new file mode 100644
index 0000000..50d991a
--- /dev/null
+++ b/include/lib/fconf/fconf_mpmm_getter.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef FCONF_MPMM_GETTER_H
+#define FCONF_MPMM_GETTER_H
+
+#include <lib/mpmm/mpmm.h>
+
+#define mpmm__config_getter(id)	fconf_mpmm_config.id
+
+struct fconf_mpmm_config {
+	const struct mpmm_topology *topology;
+};
+
+extern struct fconf_mpmm_config fconf_mpmm_config;
+
+#endif /* FCONF_MPMM_GETTER_H */