Include private/fs_config.h directly when needed

This is no longer a transitive include of android_filesystem_config.h

Bug: 149785767
Test: build
Change-Id: Ib546dbc3b6f546ba48009cc9d6d0f4564acf0872
diff --git a/tools/fs_get_stats/fs_get_stats.c b/tools/fs_get_stats/fs_get_stats.c
index 159e2aa..64ef0e2 100644
--- a/tools/fs_get_stats/fs_get_stats.c
+++ b/tools/fs_get_stats/fs_get_stats.c
@@ -4,6 +4,7 @@
 #include <unistd.h>
 
 #include <private/android_filesystem_config.h>
+#include <private/fs_config.h>
 
 #define DO_DEBUG 1