Revert "8250: Fix tcsetattr to avoid ioctl(TIOCMIWAIT) hang"

This reverts commit 47d3904fe40d62deee8cd46e79ca784e7a548acd.

Crashes any x86 serial console bootup:

  Console: colour VGA+ 80x25
  BUG: unable to handle kernel NULL pointer dereference at 0000000000000158
  IP: [<ffffffff811ebcb4>] serial8250_do_set_termios+0x1d4/0x430
  ...

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Greg KH <gregkh@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>