btrfs: move btrfs_compression_type to compression.h

So that its better organized.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_map.c

@@ -4,6 +4,7 @@
 #include <linux/hardirq.h>
 #include "ctree.h"
 #include "extent_map.h"
+#include "compression.h"
 
 
 static struct kmem_cache *extent_map_cache;