vpnor: Rename mboxd_pnor_partition_table sources to backend

Change-Id: I6f0fff4ab54e011c1765fc04186e899754787641
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/vpnor/test/dump_flash.cpp b/vpnor/test/dump_flash.cpp
index f285a61..2d5dc5d 100644
--- a/vpnor/test/dump_flash.cpp
+++ b/vpnor/test/dump_flash.cpp
@@ -14,7 +14,7 @@
 #include <cassert>
 #include <cstring>
 
-#include "vpnor/mboxd_pnor_partition_table.h"
+#include "vpnor/backend.h"
 
 struct test_context
 {