m68k: Use asm-generic/ioctls.h (enables termiox)

This patch converts m68k to use asm-generic/ioctls.h instead of its
own version.

The differences between the arch-specific version and the generic
version are as follows:

- m68k defines its own value for FIOQSIZE, asm-generic/ioctls.h keeps it
- The generic version adds TIOCSRS485 and TIOCGRS485m which are unused
  by any driver available on this architecture.
- The generic version adds support for termiox

Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>