of/fdt: add const to char *pathp in of_scan_flat_dt()

Fixed build warning as below:

drivers/of/fdt.c: In function 'of_scan_flat_dt':
drivers/of/fdt.c:490:10: warning: assignment discards 'const' qualifier from pointer target type [enabled by default]

---
This patch is based on linux-next-20121109 code tree.

 drivers/of/fdt.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

index 0ca0f9e..738228f 100644
@@ -459,7 +459,7 @@ int __init of_scan_flat_dt(int (*it)(unsigned long node,
 
 	do {
 		u32 tag = be32_to_cpup((__be32 *)p);
-		char *pathp;
+		const char *pathp;
 
 		p += 4;
 		if (tag == OF_DT_END_NODE) {

1.7.1