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/include/linux/device-mapper.h b/include/linux/device-mapper.h
index bdd65e9..eb75363 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -221,18 +221,18 @@
 	 * Set if this target needs to receive discards regardless of
 	 * whether or not its underlying devices have support.
 	 */
-	unsigned discards_supported:1;
+	bool discards_supported:1;
 
 	/*
 	 * Set if the target required discard request to be split
 	 * on max_io_len boundary.
 	 */
-	unsigned split_discard_requests:1;
+	bool split_discard_requests:1;
 
 	/*
 	 * Set if this target does not return zeroes on discarded blocks.
 	 */
-	unsigned discard_zeroes_data_unsupported:1;
+	bool discard_zeroes_data_unsupported:1;
 };
 
 /* Each target can link one of these into the table */