pwcli: cmd_stg_list(): use self.output
pwcli: cmd_stg_list(): use self.output

The function was using print() by accident, use self.output() instead.

Signed-off-by: Kalle Valo <7081a7d99b8c74c0698a728df19e3915a995d7e1@codeaurora.org>

kvalo/pwcli,kvalo/pwcli