ipaccess: Set bfd->data to NULL before releasing its reference

Since the reference is dropped, make sure no one accesses it through
that pointer anymore. It must be done before calling the put() method,
otherwise it may already be released when put() returns.

Change-Id: Ic3f261b2a995efcbc8eece9669ee3ae63af7b5c0
diff --git a/src/input/ipaccess.c b/src/input/ipaccess.c
index 4d55e71..3ff59f4 100644
--- a/src/input/ipaccess.c
+++ b/src/input/ipaccess.c
@@ -661,6 +661,7 @@
 err_line:
 	close(bfd->fd);
 	bfd->fd = -1;
+	bfd->data = NULL;
 	e1inp_line_put2(line, "ipa_bfd");
 	return ret;
 }
@@ -711,6 +712,7 @@
 err_line:
 	close(bfd->fd);
 	bfd->fd = -1;
+	bfd->data = NULL;
 	e1inp_line_put2(line, "ipa_bfd");
 	return ret;
 }