btrfs-progs: completion: add fi and dev usage commands

Signed-off-by: David Sterba <dsterba@suse.cz>

Author: kdave

btrfs-completion

@@ -31,9 +31,9 @@ _btrfs()
 
     commands='subvolume filesystem balance device scrub check rescue restore inspect-internal property send receive quota qgroup replace help version'
     commands_subvolume='create delete list snapshot find-new get-default set-default show sync'
-    commands_filesystem='defragment sync resize show df label'
+    commands_filesystem='defragment sync resize show df label usage'
     commands_balance='start pause cancel resume status'
-    commands_device='scan add delete ready stats'
+    commands_device='scan add delete ready stats usage'
     commands_scrub='start cancel resume status'
     commands_rescue='chunk-recover super-recover'
     commands_inspect_internal='inode-resolve logical-resolve subvolid-resolve rootid'