Use stable version 1.0.1 of gPXE.

diff --git a/gpxe b/gpxe
index c780ec88551e0ecee345025946702aace1dda500..ed893934d6de3698eb10413e9cf7227276e83fee 160000 (submodule)
--- a/gpxe
+++ b/gpxe
@@ -1 +1 @@
-Subproject commit c780ec88551e0ecee345025946702aace1dda500
+Subproject commit ed893934d6de3698eb10413e9cf7227276e83fee