ring_buffer: add remaining cpu functions to ring_buffer.h

These functions are not yet in ring_buffer.h though they seems to be
part of the API.

Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Robert Richter <robert.richter@amd.com>
diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
index e097c2e..de9d8c1 100644
--- a/include/linux/ring_buffer.h
+++ b/include/linux/ring_buffer.h
@@ -116,6 +116,8 @@
 
 unsigned long ring_buffer_entries(struct ring_buffer *buffer);
 unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
+unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
+unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
 
 u64 ring_buffer_time_stamp(int cpu);
 void ring_buffer_normalize_time_stamp(int cpu, u64 *ts);