tty: Split tty_port into its own file

Not much in it yet but this will grow a lot

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --cc drivers/char/Makefile
Simple merge

diff --cc drivers/char/tty_io.c
Simple merge

diff --cc drivers/char/tty_port.c
Simple merge