Fixed error in 'getbalance' when using watchonly addresses.
Fixed error in 'getbalance' when using watchonly addresses.

Rebased-from: d512534cd71ebdb67bf0cb2a377dc7c2b06ba438 #4525

litecoin-project/bitcoinomg,litecoin-project/bitcoinomg,litecoin-project/bitcoinomg,litecoin-project/bitcoinomg