Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/Documentation/driver-api/i3c/index.rst b/Documentation/driver-api/i3c/index.rst
new file mode 100644
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+++ b/Documentation/driver-api/i3c/index.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+I3C subsystem
+=============
+
+.. toctree::
+
+   protocol
+   device-driver-api
+   master-driver-api