reset upstream subtrees to HEAD

Reset the following subtrees on HEAD:
  poky: 8217b477a1(master)
  meta-xilinx: 64aa3d35ae(master)
  meta-openembedded: 0435c9e193(master)
  meta-raspberrypi: 490a4441ac(master)
  meta-security: cb6d1c85ee(master)

Squashed patches:
  meta-phosphor: drop systemd 239 patches
  meta-phosphor: mrw-api: use correct install path

Change-Id: I268e2646d9174ad305630c6bbd3fbc1a6105f43d
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/poky/documentation/overview-manual/overview-manual.xml b/poky/documentation/overview-manual/overview-manual.xml
index 320ca35..b23c394 100644
--- a/poky/documentation/overview-manual/overview-manual.xml
+++ b/poky/documentation/overview-manual/overview-manual.xml
@@ -38,13 +38,8 @@
             </revision>
             <revision>
                 <revnumber>2.6</revnumber>
-                <date>November 2018</date>
-                <revremark>Released with the Yocto Project 2.6 Release.</revremark>
-            </revision>
-            <revision>
-                <revnumber>2.6.1</revnumber>
                 <date>&REL_MONTH_YEAR;</date>
-                <revremark>Released with the Yocto Project 2.6.1 Release.</revremark>
+                <revremark>Released with the Yocto Project 2.6 Release.</revremark>
             </revision>
         </revhistory>