powerpc: apply recent changes to merged code

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/of_device.c b/arch/powerpc/kernel/of_device.c
index 7667188..7065e40 100644
--- a/arch/powerpc/kernel/of_device.c
+++ b/arch/powerpc/kernel/of_device.c
@@ -4,6 +4,8 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
+#include <linux/slab.h>
+
 #include <asm/errno.h>
 #include <asm/of_device.h>