of: fdt: Constify 'pathp'

Constify 'pathp' in order to get rid of the following warning:

drivers/of/fdt.c:491:10: warning: assignment discards 'const' qualifier from pointer target type [enabled by default]
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
[Rob Herring: also constify np and lp]
Signed-off-by: Rob Herring <rob.herring@calxeda.com>

drivers/of/fdt.c

@@ -460,7 +460,7 @@ 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) {
@@ -488,7 +488,7 @@ int __init of_scan_flat_dt(int (*it)(unsigned long node,
 		pathp = (char *)p;
 		p = ALIGN(p + strlen(pathp) + 1, 4);
 		if ((*pathp) == '/') {
-			char *lp, *np;
+			const char *lp, *np;
 			for (lp = NULL, np = pathp; *np; np++)
 				if ((*np) == '/')
 					lp = np+1;