mtd: partitions: make parsers return 'const' partition arrays

We only want to modify these arrays inside the parser "drivers", so the
drivers should construct them however they like, then return them as
immutable arrays.

This will make other refactorings easier.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/afs.c

@@ -162,7 +162,7 @@ afs_read_iis_v1(struct mtd_info *mtd, struct image_info_v1 *iis, u_int ptr)
 }
 
 static int parse_afs_partitions(struct mtd_info *mtd,
-				struct mtd_partition **pparts,
+				const struct mtd_partition **pparts,
 				struct mtd_part_parser_data *data)
 {
 	struct mtd_partition *parts;