mtd: physmap: add const qualifiers

Be a bit stricter and add few more 'const' qualifiers.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/include/linux/mtd/physmap.h b/include/linux/mtd/physmap.h
index d2887e7..aa6a263 100644
--- a/include/linux/mtd/physmap.h
+++ b/include/linux/mtd/physmap.h
@@ -30,7 +30,7 @@
 	unsigned int		pfow_base;
 	char                    *probe_type;
 	struct mtd_partition	*parts;
-	const char		**part_probe_types;
+	const char * const	*part_probe_types;
 };
 
 #endif /* __LINUX_MTD_PHYSMAP__ */