[POWERPC] Disable vDSO support for ARCH=ppc where it's not implemented

Signed-off-by: Wolfgang Denk <wd@denx.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 213fa31..2322ba5 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -766,7 +766,9 @@
 
 	return 0;
 }
+#ifdef CONFIG_PPC_MERGE
 arch_initcall(vdso_init);
+#endif
 
 int in_gate_area_no_task(unsigned long addr)
 {