iomap: start moving code to fs/iomap/

Create the build infrastructure we need to start migrating iomap code to
fs/iomap/ from fs/iomap.c.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/iomap/Makefile b/fs/iomap/Makefile
new file mode 100644
index 0000000..de5a1f9
--- /dev/null
+++ b/fs/iomap/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0-or-newer
+#
+# Copyright (c) 2019 Oracle.
+# All Rights Reserved.
+#