block/partitions/mac.c: obey the state->limit constraint

It isn't necessary to read the information of partitions whose number is
equal and more than state->limit since only maximum state->limit
partitions will be added inside rescan_partitions().

That is also what other kind of partitions are doing.
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

block/partitions/mac.c

@@ -63,6 +63,10 @@ int mac_partition(struct parsed_partitions *state)
 		put_dev_sector(sect);
 		return 0;
 	}
+
+	if (blocks_in_map >= state->limit)
+		blocks_in_map = state->limit - 1;
+
 	strlcat(state->pp_buf, " [mac]", PAGE_SIZE);
 	for (slot = 1; slot <= blocks_in_map; ++slot) {
 		int pos = slot * secsize;