Enable v8.6 AMU enhancements (FEAT_AMUv1p1)

ARMv8.6 adds virtual offset registers to support virtualization of the
event counters in EL1 and EL0.  This patch enables support for this
feature in EL3 firmware.

Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: I7ee1f3d9f554930bf5ef6f3d492e932e6d95b217
diff --git a/include/lib/extensions/amu_private.h b/include/lib/extensions/amu_private.h
index 30ce59d..3b4b47c 100644
--- a/include/lib/extensions/amu_private.h
+++ b/include/lib/extensions/amu_private.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2020, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2021, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -16,4 +16,12 @@
 void amu_group1_cnt_write_internal(unsigned int idx, uint64_t val);
 void amu_group1_set_evtype_internal(unsigned int idx, unsigned int val);
 
+#if __aarch64__
+uint64_t amu_group0_voffset_read_internal(unsigned int idx);
+void amu_group0_voffset_write_internal(unsigned int idx, uint64_t val);
+
+uint64_t amu_group1_voffset_read_internal(unsigned int idx);
+void amu_group1_voffset_write_internal(unsigned int idx, uint64_t val);
+#endif
+
 #endif /* AMU_PRIVATE_H */