AMU: Fix failures in daily builds

This fixes an include issue with the AMU header files.

Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: I6e884d4ba665f2ad6a84927c3337220c802cbb4c
diff --git a/include/lib/extensions/amu.h b/include/lib/extensions/amu.h
index f8301c6..d5950ca 100644
--- a/include/lib/extensions/amu.h
+++ b/include/lib/extensions/amu.h
@@ -11,6 +11,7 @@
 
 #include <cassert.h>
 #include <platform_def.h>
+#include <utils_def.h>
 
 #define AMU_GROUP0_COUNTERS_MASK	U(0xf)
 #define AMU_GROUP0_NR_COUNTERS		U(4)