tst_net.sh: Remove PASSWD

Not used any more since ftp01.sh removal (the last test which was using it).

Follow-up: b8531de ("tcp_cmds: Remove ftp01.sh test, binary data files")
Signed-off-by: Petr Vorel <pvorel@suse.cz>

Author: pevik

testcases/lib/tst_net.sh

@@ -1144,7 +1144,6 @@ tst_net_detect_ipv6
 # Management Link
 [ -z "$RHOST" ] && TST_USE_NETNS="yes"
 export RHOST="$RHOST"
-export PASSWD="${PASSWD:-}"
 # Don't use it in new tests, use tst_rhost_run() from tst_net.sh instead.
 export LTP_RSH="${LTP_RSH:-ssh -nq}"