[S390] cio: Introduce abstract isc definitions.

Replace the numeric values for I/O interruption subclass usage
with abstract definitions and collect them all in asm/isc.h.
This gives us a better overview of which iscs are actually used
and makes it possible to better spread out isc usage in the
future.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

drivers/s390/cio/css.c

@@ -13,6 +13,7 @@
 #include <linux/errno.h>
 #include <linux/list.h>
 #include <linux/reboot.h>
+#include <asm/isc.h>
 
 #include "../s390mach.h"
 #include "css.h"
@@ -804,7 +805,8 @@ init_channel_subsystem (void)
 		goto out_pseudo;
 	css_init_done = 1;
 
-	ctl_set_bit(6, 28);
+	/* Enable default isc for I/O subchannels. */
+	ctl_set_bit(6, 31 - IO_SCH_ISC);
 
 	for_each_subchannel(__init_channel_subsystem, NULL);
 	return 0;