xfs: remove leftovers of the old btree tracing code

Remove various bits left over from the old kdb-only btree tracing code, but
leave the actual trace point stubs in place to ease adding new event based
btree tracing.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/xfs_btree.c

@@ -32,7 +32,6 @@
 #include "xfs_inode.h"
 #include "xfs_inode_item.h"
 #include "xfs_btree.h"
-#include "xfs_btree_trace.h"
 #include "xfs_error.h"
 #include "xfs_trace.h"