btrfs: fix dereference of ERR_PTR value

smatch reports:

btrfs_recover_log_trees error: 'wc.replay_dest' dereferencing
possible ERR_PTR()

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
1 file changed