ftp: fix LIST, NLST and MLSD cmd-channel output

A recent patch, committed as b72f2b5283c7a1f3bdd7b7f2c7e5313802a1dff2,
added support for the delayed passive mode.  Unfortunately, it
also broke the LIST, NLST and MLSD output as it placed the "150"
response on the wrong branch of an if-statement.

Although our functional tests failed to detect the problem, Globus
(formally known as GlobusOnline) fails if the 150 message is missing.

This patch moves the reply to the correct branch, fixing Globus

Request: 1.9
Target: master
Require-notes: yes
Require-book: no