Updated PXE UDP implementation to use the new Etherboot UDP API.

Updated PXE API dispatcher to use copy_{to,from}_user, and moved to
arch/i386 since the implementation is quite architecture-dependent.
(The individual PXE API calls can be largely
architecture-independent.)

src/interface/pxe/pxe_preboot.c

@@ -23,6 +23,8 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+#if 0
+
 #include "pxe.h"
 #include "pxe_callbacks.h"
 
@@ -247,3 +249,5 @@ PXENV_EXIT_t pxenv_stop_base ( struct s_PXENV_STOP_BASE *stop_base ) {
 	stop_base->Status = PXENV_STATUS_SUCCESS;
 	return PXENV_EXIT_SUCCESS;
 }
+
+#endif