Change how we change the lcd density

This allows us to edit the props without re-zipping

Change-Id: I6d59ecf79f765009e57deabccd5de074b7a7d006
diff --git a/config/common.mk b/config/common.mk
index 66618e8..b0e2436 100644
--- a/config/common.mk
+++ b/config/common.mk
@@ -176,3 +176,5 @@
     ro.modversion=$(SLIM_MOD_VERSION) \
     ro.slim.buildtype=$(SLIM_BUILD_TYPE)
 
+EXTENDED_POST_PROCESS_PROPS := vendor/slim/tools/slim_process_props.py
+