oprofile: add op_cpu_buffer_add_data()

This function can be used to attach data to a sample. It returns the
remaining free buffer size that has been reserved with
op_cpu_buffer_write_reserve().

Signed-off-by: Robert Richter <robert.richter@amd.com>
diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c
index e859d23..1b65907 100644
--- a/drivers/oprofile/cpu_buffer.c
+++ b/drivers/oprofile/cpu_buffer.c
@@ -258,7 +258,7 @@
 	sample->event = flags;
 
 	if (size)
-		sample->data[0] = (unsigned long)task;
+		op_cpu_buffer_add_data(&entry, (unsigned long)task);
 
 	op_cpu_buffer_write_commit(&entry);