[S390] Move private simple udelay function to arch/s390/lib/delay.c.

Move cio's private simple udelay function to lib/delay.c and turn it
into something much more readable. So we have all implementations
at one place.

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 7835731..a356c95 100644
--- a/arch/s390/include/asm/delay.h
+++ b/arch/s390/include/asm/delay.h
@@ -15,6 +15,7 @@
 #define _S390_DELAY_H
 
 extern void __udelay(unsigned long usecs);
+extern void udelay_simple(unsigned long usecs);
 extern void __delay(unsigned long loops);
 
 #define udelay(n) __udelay(n)