The state was introduced in commit 4a9d8bde ("Btrfs: make the state
of the transaction more readable"), then in commit 302167c5
("btrfs: don't end the transaction for delayed refs in throttle") the
state is completely removed.

So we can just clean up the state since it's only compared but never
set.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>