tracing: make all file_operations const

Impact: cleanup

All file_operations structures should be constant. No one is going to
change them.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index f747364..1788584 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2606,7 +2606,7 @@
 	return cnt;
 }
 
-static struct file_operations rb_simple_fops = {
+static const struct file_operations rb_simple_fops = {
 	.open		= tracing_open_generic,
 	.read		= rb_simple_read,
 	.write		= rb_simple_write,