Init: Fix literal

This is a literal 0 implicitly converted to a NULL.

Change-Id: I0573e85eb0578f938877c4bec79054081c27e661
diff --git a/init/init.c b/init/init.c
index 096d898..8bb6da0 100644
--- a/init/init.c
+++ b/init/init.c
@@ -349,7 +349,7 @@
                 if (arg_idx == INIT_PARSER_MAXARGS)
                     break;
             }
-            arg_ptrs[arg_idx] = '\0';
+            arg_ptrs[arg_idx] = NULL;
             execve(svc->args[0], (char**) arg_ptrs, (char**) ENV);
         }
         _exit(127);