Revert "Add missing external/lz4"

This reverts commit 6c3527655f1749e58a4bec4d641a61811ac20179.
diff --git a/default.xml b/default.xml
index fd237b8..af72600 100644
--- a/default.xml
+++ b/default.xml
@@ -438,5 +438,4 @@
   <project name="fp2/vendor/fairphone/packages/apps/ProximitySensor" path="vendor/fairphone/packages/apps/ProximitySensor" revision="refs/tags/release_2.2.1-MR2"/>
   <project name="fp2/system/extras/appops_su" path="system/extras/appops_su" />
   <project name="fp2/platform/external/busybox" path="external/busybox" revision="fp2-m-sibon" />
-  <project name="fp2/platform/external/lz4" path="external/lz4" />
 </manifest>