[loader] Set SYSCONF to /config

This updates the loader to look for Vulkan configuration data in
/config instead of /system/data.

Test: Boot and load up Vulkan driver
Change-Id: I025ee69519fb9d89567832f210d9e29c788de06f
diff --git a/loader/BUILD.gn b/loader/BUILD.gn
index 6940b86..c8ef558 100644
--- a/loader/BUILD.gn
+++ b/loader/BUILD.gn
@@ -52,7 +52,7 @@
 
   cflags_c = [
     "-Wno-missing-field-initializers",
-    "-DSYSCONFDIR=\"/system/data\"",
+    "-DSYSCONFDIR=\"/config\"",
     "-DDATADIR=\"/usr/share\"",
   ]