The bank should not concern about where the funds are coming from and their's is to serve the clients or the customers of the bank and not to investigate the client private transaction. And letting the bank to know that you holding bitcoin or cryptocurrency is not a bad thing and all depends on the country. If you are in a country that loves cryptocurrency then you are free to tell the bank that you are a cryptocurrency investor. But whereby the country you living in does not accept bitcoin or ban bitcoin then you don't have to expose yourself to anyone to avoid unnecessary embarrassment or harassment.

Stay clear and safe avoid those those who hate bitcoin.