compat: fix compile breakage on s390

The new is_compat_task() define for the !COMPAT case in
include/linux/compat.h conflicts with a similar define in
arch/s390/include/asm/compat.h.

This is the minimal patch which fixes the build issues.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/s390/block/dasd_ioctl.c b/drivers/s390/block/dasd_ioctl.c
index f1a2016..792c69e 100644
--- a/drivers/s390/block/dasd_ioctl.c
+++ b/drivers/s390/block/dasd_ioctl.c
@@ -13,6 +13,7 @@
 #define KMSG_COMPONENT "dasd"
 
 #include <linux/interrupt.h>
+#include <linux/compat.h>
 #include <linux/major.h>
 #include <linux/fs.h>
 #include <linux/blkpg.h>