net: Add bootfile in DHCP Request

Add the bootfile name in the DHCP Request packet, in addition
to it already being sent in the DHCP Discover.

This is needed by some DHCP servers so that the bootfile name is
properly returned by the server to the client in the DHCP Ack, as
expected by U-Boot.

Signed-off-by: Alexandre Messier <amessier@tycoint.com>

net/bootp.c

@@ -949,6 +949,7 @@ static void dhcp_send_request_packet(struct bootp_hdr *bp_offer)
 	net_write_ip(&bp->bp_giaddr, zero_ip);
 
 	memcpy(bp->bp_chaddr, net_ethaddr, 6);
+	copy_filename(bp->bp_file, net_boot_file_name, sizeof(bp->bp_file));
 
 	/*
 	 * ID is the id of the OFFER packet