cli/polkit-agent: drop an extra newline

It looks bad and makes everyone super-sad:

  $ nmcli --ask c modify 'Oracle HQ' 802-11-wireless-security.psk solaris666
  System policy prevents modification of network settings for all users
  (action_id: org.freedesktop.NetworkManager.settings.modify.system)
  Password (lkundrak): *********

  $

(cherry picked from commit de9b74452c)

clients/cli/polkit-agent.c

@@ -57,7 +57,6 @@ polkit_request (const char *request,
 		g_free (tmp);
 	} else
 		response = nmc_readline_echo (echo_on, "%s", request);
-	g_print ("\n");
 
 	return response;
 }