[PATCH] radio modems sitting on serial port are not for s390

Won't build (request_irq()/free_irq()), even if you manage to find an
s390 box with 8250-compatible UART they are expecting.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>