busybox-inittab: fix console handling

busybox-inittab: fix console handling

A testing failure meant that the inittab changes made in 6c65544 didn't
actually work.

A copy-paste problems meant that start_getty was being invoked instead
of getty, but start_getty is sysvinit-inittab-specific. Revert this
inittab to calling getty directly.

Remove the terminal type, this wasn't specified in the original inittab.

Busybox's init has non-standard behaviour for the inittab's ID field.
With SysV this is a four-character identifier and nothing more, but with
busybox init this is the controlling terminal (minus /dev).  If the
terminal doesn't exist then busybox doesn't gracefully handle the
failure but instead repeatedly fails to spawn.

As getty will immediately issue a setsid() this isn't needed for getty
entries, so the ID can be empty and ttyrun does the terminal detection.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>