The fallback path covers not just ARM64, need this for Power as well.

Change-Id: I7bbf76f77bd3ac47a0a0987c1e880e23834588e2

runtime/hsa-runtime/core/util/timer.h

@@ -147,8 +147,7 @@ class fast_clock {
 #ifdef __x86_64__
   static __forceinline raw_rep raw_now() { return __rdtsc(); }
   static __forceinline raw_frequency raw_freq() { return freq; }
-#endif
-#ifdef __aarch64__
+#else
   static __forceinline raw_rep raw_now() {
     struct timespec ts;
     clock_gettime(CLOCK_MONOTONIC_RAW, &ts);

runtime/hsa-runtime/core/util/utils.h

@@ -56,11 +56,6 @@ typedef uint64_t uint64;
 #if defined(__GNUC__)
 #if defined(__i386__) || defined(__x86_64__)
 #include <x86intrin.h>
-#elif defined(__aarch64__)
-#else
-#error \
-    "Processor or compiler not identified.  " \
-    "Need to provide a lightweight approximate clock interface via function uint64_t __rdtsc() or adapt timer.h to your platform."
 #endif
 
 #define __forceinline __inline__ __attribute__((always_inline))