Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/Documentation/s390/index.rst b/Documentation/s390/index.rst
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+=================
+s390 Architecture
+=================
+
+.. toctree::
+    :maxdepth: 1
+
+    cds
+    3270
+    driver-model
+    monreader
+    qeth
+    s390dbf
+    vfio-ap
+    vfio-ccw
+    zfcpdump
+    common_io
+
+    text_files
+
+.. only::  subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`