Revert "poky: subtree update:b23aa6b753..ad30a6d470"

This reverts commit af5e4ef732faedf66c6dc1756432e9de2ac72988.

This commit introduced openbmc/openbmc#3720 and no solution has been
forthcoming. Revert until we can get to the bottom of this.

Change-Id: I2fb0d81eb26cf3dadb2f2abdd1a1bb7a95eaf03c
diff --git a/poky/documentation/ref-manual/ref-system-requirements.rst b/poky/documentation/ref-manual/ref-system-requirements.rst
index 54f38f6..56218e4 100644
--- a/poky/documentation/ref-manual/ref-system-requirements.rst
+++ b/poky/documentation/ref-manual/ref-system-requirements.rst
@@ -1,4 +1,4 @@
-.. SPDX-License-Identifier: CC-BY-SA-2.0-UK
+.. SPDX-License-Identifier: CC-BY-2.0-UK
 
 *******************
 System Requirements