dm: use bool bitfields in struct dm_target

Use boolean bit fields for flags in struct dm_target.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 330f1ea..00a25ab 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1694,7 +1694,7 @@
 	}
 
 	ti->num_flush_requests = 1;
-	ti->discard_zeroes_data_unsupported = 1;
+	ti->discard_zeroes_data_unsupported = true;
 
 	return 0;