kbuild: alpha,x86_64 use generic asm-offsets.h support

Delete obsolete stuff from arch makefiles
Rename .h file to asm-offsets.h

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/arch/x86_64/lib/putuser.S b/arch/x86_64/lib/putuser.S
index 5828b81..7f55939 100644
--- a/arch/x86_64/lib/putuser.S
+++ b/arch/x86_64/lib/putuser.S
@@ -27,7 +27,7 @@
 #include <linux/linkage.h>
 #include <asm/page.h>
 #include <asm/errno.h>
-#include <asm/offset.h>
+#include <asm/asm-offsets.h>
 #include <asm/thread_info.h>
 
 	.text