Fix fetching auth account for params CLI

[shanev]

• [ ] Linked to Github issues that this PR fixes (if any)
• [ ] Wrote tests
• [ ] Updated README.md if needed
• [ ] Updated docs/spec if needed
• [x] Tested running truchain, truapi, and truapp locally (https://gist.github.com/shanev/3897a80072ac4147677fa596ada497fb)

Tested on devnet:

$ truchaincli params staking cosmos1tfpcnjzkthft3ynewqvn7mtdk7guf3knjdqg4d --upvote_stake 30000000000tru --chain-id devnet-n --home ~/.octopus                                                                                      [1:06:20]
Password to sign with 'reward_broker':
Response:
  Height: 351922
  TxHash: EF4C58DD8AC5A4C721F1E5F6DC420F805679D47E864B7F74BF76298308C457A3
  Data: 74727565
  Raw Log: [{"msg_index":0,"success":true,"log":""}]
  Logs: [{"msg_index":0,"success":true,"log":""}]
  GasUsed: 110280
  Events:
        - message
            - action: update_params