[S390] delay: implement ndelay

Implement ndelay() on s390 as well.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/delay.h b/arch/s390/include/asm/delay.h
index 8a096b8..0e3b35f 100644
--- a/arch/s390/include/asm/delay.h
+++ b/arch/s390/include/asm/delay.h
@@ -14,10 +14,12 @@
 #ifndef _S390_DELAY_H
 #define _S390_DELAY_H
 
-extern void __udelay(unsigned long long usecs);
-extern void udelay_simple(unsigned long long usecs);
-extern void __delay(unsigned long loops);
+void __ndelay(unsigned long long nsecs);
+void __udelay(unsigned long long usecs);
+void udelay_simple(unsigned long long usecs);
+void __delay(unsigned long loops);
 
+#define ndelay(n) __ndelay((unsigned long long) (n))
 #define udelay(n) __udelay((unsigned long long) (n))
 #define mdelay(n) __udelay((unsigned long long) (n) * 1000)