AMU: Add configuration helpers for aarch64

Add some AMU helper functions to allow configuring, reading and
writing of the Group 0 and Group 1 counters.  Documentation for these
helpers will come in a separate patch.

Change-Id: I656e070d2dae830c22414f694aa655341d4e2c40
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>
diff --git a/include/lib/extensions/amu_private.h b/include/lib/extensions/amu_private.h
new file mode 100644
index 0000000..0c660bb
--- /dev/null
+++ b/include/lib/extensions/amu_private.h
@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __AMU_PRIVATE_H__
+#define __AMU_PRIVATE_H__
+
+#include <stdint.h>
+
+uint64_t amu_group0_cnt_read_internal(int idx);
+void amu_group0_cnt_write_internal(int idx, uint64_t);
+
+uint64_t amu_group1_cnt_read_internal(int idx);
+void amu_group1_cnt_write_internal(int idx, uint64_t);
+void amu_group1_set_evtype_internal(int idx, unsigned int val);
+
+#endif /* __AMU_PRIVATE_H__ */