ioctl: Use asm-generic/ioctls.h on s390 (enables termiox)

This patch converts s390 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:

- S390 defines its own value for FIOQSIZE, asm-generic/ioctls.h keeps it
- The generic version adds TIOCGRS485 and TIOCGRS485, which are unused
  by any driver available on this architecture
- The generic version adds support for termiox

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>