MIPS: prepare for user enabling of CONFIG_OF

In preparation to allow users to enable DeviceTree without arch or
machine selecting it, we need to fix build errors on MIPS. When
CONFIG_OF is enabled, device_tree_init cannot be resolved. This is
trivially fixed by using CONFIG_USE_OF instead of CONFIG_OF for prom.h.
Signed-off-by: NRob Herring <robh@kernel.org>
Acked-by: NRalf Baechle <ralf@linux-mips.org>
Acked-by: NGrant Likely <grant.likely@lianro.org>
Cc: linux-mips@linux-mips.org

arch/mips/include/asm/prom.h

@@ -11,7 +11,7 @@
 #ifndef __ASM_PROM_H
 #define __ASM_PROM_H
 
-#ifdef CONFIG_OF
+#ifdef CONFIG_USE_OF
 #include <linux/bug.h>
 #include <linux/io.h>
 #include <linux/types.h>

arch/mips/kernel/prom.c

@@ -18,6 +18,7 @@
 #include <linux/of_fdt.h>
 #include <linux/of_platform.h>
 
+#include <asm/bootinfo.h>
 #include <asm/page.h>
 #include <asm/prom.h>