tools: Optimize ring buffer for riscv

Now that the riscv tools tree supports optimized barriers, use them in
the ring buffer.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Andrea Parri <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20240806-optimize_ring_buffer_read_riscv-v2-2-ca7e193ae198@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: charlie-rivos

tools/include/linux/ring_buffer.h

@@ -55,7 +55,7 @@ static inline u64 ring_buffer_read_head(struct perf_event_mmap_page *base)
  * READ_ONCE() + smp_mb() pair.
  */
 #if defined(__x86_64__) || defined(__aarch64__) || defined(__powerpc64__) || \
-    defined(__ia64__) || defined(__sparc__) && defined(__arch64__)
+    defined(__ia64__) || defined(__sparc__) && defined(__arch64__) || defined(__riscv)
 	return smp_load_acquire(&base->data_head);
 #else
 	u64 head = READ_ONCE(base->data_head);