symbol: Remove various bits of left over junk

There are various bits of code here that are unfinished and instead of
being harmless either confuse or spew stuff into the logs at higher than
debug level. They can and should go away.

Also remove the bogus use of tty->lowlatency. We fixed the need for this hack
long ago (with the flip buffer rewrite) but people keep copying it into drivers.

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>