btrfs: remove the second argument of k[un]map_atomic()

Signed-off-by: Cong Wang <amwang@redhat.com>
diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c
index a178f5e..743b86f 100644
--- a/fs/btrfs/lzo.c
+++ b/fs/btrfs/lzo.c
@@ -411,9 +411,9 @@
 
 	bytes = min_t(unsigned long, destlen, out_len - start_byte);
 
-	kaddr = kmap_atomic(dest_page, KM_USER0);
+	kaddr = kmap_atomic(dest_page);
 	memcpy(kaddr, workspace->buf + start_byte, bytes);
-	kunmap_atomic(kaddr, KM_USER0);
+	kunmap_atomic(kaddr);
 out:
 	return ret;
 }