dm table: remove unused dm_get_device range parameters

Remove unused parameters(start and len) of dm_get_device()
and fix the callers.

Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index de26fde..6d66ddf 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -920,8 +920,7 @@
 		return -EINVAL;
 	}
 
-	if (dm_get_device(ti, argv[0], offset, ti->len,
-			  dm_table_get_mode(ti->table),
+	if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
 			  &ms->mirror[mirror].dev)) {
 		ti->error = "Device lookup failure";
 		return -ENXIO;