proposed change to getty

[Jared McNeill <jmcneill%invisible.ca@localhost>]

There's a 2 second sleep in getty before opening the tty that has been 
there since before NetBSD and I am planning to get rid of it. The comment 
above it says:

	 * Delay the open so DTR stays down long enough
	 * to be detected.

A bunch of our uart drivers already have a similar workaround in their 
chardev close functions so it should not be necessary in most cases. 
Question is -- is anybody relying on this behaviour anymore? If so I can 
help fix your serial driver.

getty source: https://nxr.netbsd.org/xref/src/libexec/getty/main.c#232

Take care,
Jared