s390/chpid: make headers usable (again)

Add back a hunk from "4dcc2a4d s390/chsc: make headers usable"
which was lost during the merge of the UAPI patch.
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/uapi/asm/chpid.h

 /*
- *    Copyright IBM Corp. 2007
+ *    Copyright IBM Corp. 2007, 2012
  *    Author(s): Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
  */
 
@@ -12,10 +12,10 @@
 #define __MAX_CHPID 255
 
 struct chp_id {
-	u8 reserved1;
-	u8 cssid;
-	u8 reserved2;
-	u8 id;
+	__u8 reserved1;
+	__u8 cssid;
+	__u8 reserved2;
+	__u8 id;
 } __attribute__((packed));