[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/Makefile

@@ -80,6 +80,7 @@ SRCDIRS		+= arch/i386/drivers
 SRCDIRS		+= arch/i386/drivers/net
 SRCDIRS		+= arch/i386/interface/pcbios
 SRCDIRS		+= arch/i386/interface/pxe
+SRCDIRS		+= arch/i386/interface/pxeparent
 SRCDIRS 	+= arch/i386/interface/syslinux
 SRCDIRS		+= arch/i386/hci/commands
 

src/arch/i386/drivers/net/undiisr.S

@@ -31,7 +31,7 @@ undiisr:
 	movw	%ax, %ds
 
 	/* Check that we have an UNDI entry point */
-	cmpw	$0, undinet_entry_point
+	cmpw	$0, pxeparent_entry_point
 	je	chain
 
 	/* Issue UNDI API call */
@@ -42,7 +42,7 @@ undiisr:
 	pushw	%es
 	pushw	%di
 	pushw	%bx
-	lcall	*undinet_entry_point
+	lcall	*pxeparent_entry_point
 	cli	/* Just in case */
 	addw	$6, %sp
 	cmpw	$PXENV_UNDI_ISR_OUT_OURS, funcflag