[S390] Make user-copy operations run-time configurable.

Introduces a struct uaccess_ops which allows setting user-copy
operations at run-time.

Signed-off-by: Gerald Schaefer <geraldsc@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/lib/Makefile b/arch/s390/lib/Makefile
index e05d087..96c8242 100644
--- a/arch/s390/lib/Makefile
+++ b/arch/s390/lib/Makefile
@@ -4,6 +4,5 @@
 
 EXTRA_AFLAGS := -traditional
 
-lib-y += delay.o string.o
-lib-y += $(if $(CONFIG_64BIT),uaccess64.o,uaccess.o)
+lib-y += delay.o string.o uaccess_std.o
 lib-$(CONFIG_SMP) += spinlock.o