md/bitmap: move printing of bitmap status to bitmap.c

The part of /proc/mdstat which describes the bitmap should really
be generated by code in bitmap.c.  So move it there.

Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/bitmap.h

@@ -227,6 +227,7 @@ void bitmap_destroy(struct mddev *mddev);
 
 void bitmap_print_sb(struct bitmap *bitmap);
 void bitmap_update_sb(struct bitmap *bitmap);
+void bitmap_status(struct seq_file *seq, struct bitmap *bitmap);
 
 int  bitmap_setallbits(struct bitmap *bitmap);
 void bitmap_write_all(struct bitmap *bitmap);