[legacy] Remove long-obsolete old dhcp.h file

src/include/dhcp.h

-#ifndef DHCP_H
-#define DHCP_H
-
-#include "stdint.h"
-
-struct dhcp_dev_id {
-	uint8_t		bus_type;
-	uint16_t	vendor_id;
-	uint16_t	device_id;
-} __attribute__ (( packed ));
-
-#endif /* DHCP_H */

src/include/nic.h

 #include <gpxe/eisa.h>
 #include <gpxe/mca.h>
 #include <gpxe/io.h>
-#include "dhcp.h"
 
 typedef enum {
 	DISABLE = 0,
 	unsigned char		irqno;
 	unsigned int		mbps;
 	duplex_t		duplex;
-	struct dhcp_dev_id	dhcp_dev_id;
 	void			*priv_data;	/* driver private data */
 };