[pxe] Separate parent PXE API caller from UNDINET driver

Calling the parent PXE stack (the stack that loaded us, for
undionly.kkpxe) can be useful for more than UNDI calls; for instance,
it lets us get cached DHCP packets to avoid re-DHCP when working with
embedded images.

Signed-off-by: Marty Connor <mdc@etherboot.org>

src/arch/i386/include/pxeparent.h

@@ -0,0 +1,11 @@
+#ifndef PXEPARENT_H
+#define PXEPARENT_H
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <pxe_types.h>
+
+extern int pxeparent_call ( SEGOFF16_t entry, unsigned int function,
+			    void *params, size_t params_len );
+
+#endif