Remove pinned libxml2

This change has been in upstream for a long time.  No need to keep it
here.

Tested:
build succeeds.

Change-Id: I93b33dbc038b211f73421fa5b3e0a23485b60193
Signed-off-by: Ed Tanous <ed.tanous@intel.com>
diff --git a/meta-common/recipes-intel/libtinyxml2/libtinyxml2_%.bbappend b/meta-common/recipes-intel/libtinyxml2/libtinyxml2_%.bbappend
deleted file mode 100644
index 60cfe5e..0000000
--- a/meta-common/recipes-intel/libtinyxml2/libtinyxml2_%.bbappend
+++ /dev/null
@@ -1,3 +0,0 @@
-# update libtinyxml2 to version 6.0.0
-SRCREV = "8c8293ba8969a46947606a93ff0cb5a083aab47a"
-FILES_${PN}-dev += "${libdir}/cmake/tinyxml2/*"