system: remove use of legacy md5 option
Commit "bf3626002f system cfg: remove mkpasswd MD5 format option", from
release 2019.02, moved the symbol to legacy handling, but the symbol is
still referenced.
Remove the reference to it.
Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit 032cfbc716749869b185f83dab450ec47f969765)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>