Refactor len(w.secret) != 32
Refactor len(w.secret) != 32

Now using w.IsLocked() for all instances of above.
Also changed one other place where the logic had to be reversed
in nextChainedAddress (len(w.secret) == 32 was the condition).

jrick/btcwallet,decred/dcrwallet,synrg-labs/btcwallet,synrg-labs/btcwallet,jrick/btcwallet,btcsuite/btcwallet,jrick/dcrwallet,btcsuite/btcwallet,decred/dcrwallet,jrick/dcrwallet,Roasbeef/btcwallet,Stash-Crypto/btcwallet,Roasbeef/btcwallet,Stash-Crypto/btcwallet