oprofile: make new cpu buffer functions part of the api

This patch creates the new functions

 oprofile_write_reserve()
 oprofile_add_data()
 oprofile_write_commit()

and makes them part of the oprofile api.

Signed-off-by: Robert Richter <robert.richter@amd.com>

drivers/oprofile/cpu_buffer.h

@@ -35,13 +35,7 @@ struct op_sample {
 	unsigned long data[0];
 };
 
-struct op_entry {
-	struct ring_buffer_event *event;
-	struct op_sample *sample;
-	unsigned long irq_flags;
-	unsigned long size;
-	unsigned long *data;
-};
+struct op_entry;
 
 struct oprofile_cpu_buffer {
 	unsigned long buffer_size;