mtd: mtdcore: use const qualifier

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/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index 9ee0911..3014933 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -694,7 +694,7 @@
  * Do not forget to update 'parse_mtd_partitions()' kerneldoc comment if you
  * are changing this array!
  */
-static const char *default_mtd_part_types[] = {
+static const char * const default_mtd_part_types[] = {
 	"cmdlinepart",
 	"ofpart",
 	NULL