s390: ignore pkey system calls

Ignore the pkey systems calls since they don't make any sense on s390.
In addition any user could trigger a warning if issueing the pkey_free
system call, if it would be wired up on a system without pkey support.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/unistd.h

@@ -9,6 +9,9 @@
 #include <uapi/asm/unistd.h>
 
 #define __IGNORE_time
+#define __IGNORE_pkey_mprotect
+#define __IGNORE_pkey_alloc
+#define __IGNORE_pkey_free
 
 #define __ARCH_WANT_OLD_READDIR
 #define __ARCH_WANT_SYS_ALARM