compat: Re-add missing asm/compat.h include to fix compile breakage on s390

compat: Re-add missing asm/compat.h include to fix compile breakage on s390

For 3.0 stable kernel the backport of 048cd4e51d24ebf7f3552226d03c769d6ad91658
"compat: fix compile breakage on s390" breaks compilation...

Re-add a single #include <asm/compat.h> in order to fix this.

This patch is _not_ necessary for upstream, only for stable kernels
which include the "build fix" mentioned above.

One fix for arch/s390/kernel/setup.c was already sent and applied. But
we need a similar patch for drivers/s390/char/fs3270.c.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>