btrfs: drop newlines from strings when using btrfs_* helpers

The helpers append "\n" so we can keep the actual strings shorter. The
extra newline will print an empty line.  Some messages have been
slightly modified to be more consistent with the rest (lowercase first
letter).

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 6f1e4c9..de53c521 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -3869,8 +3869,7 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
 			ro_set = 0;
 		} else {
 			btrfs_warn(fs_info,
-				   "failed setting block group ro, ret=%d\n",
-				   ret);
+				   "failed setting block group ro: %d", ret);
 			btrfs_put_block_group(cache);
 			break;
 		}