main: don't force text mode in console_setup()

main: don't force text mode in console_setup()

When systemd starts, plymouth may be already displaying progress
graphically. Do not switch the console to text mode at that time.
All other users of reset_terminal_fd() do the switch as before.

This avoids a graphical glitch with plymouth, especially visible with
vesafb, but could be also seen as a sub-second blink with radeon.

https://bugzilla.redhat.com/show_bug.cgi?id=785548