Remove part_ prefix

partmap/acorn.c

@@ -131,7 +131,7 @@ acorn_partition_map_iterate (grub_disk_t disk,
 /* Partition map type.  */
 static struct grub_partition_map grub_acorn_partition_map =
 {
-  .name = "part_acorn",
+  .name = "acorn",
   .iterate = acorn_partition_map_iterate,
 };