net: remove CONFIG_MCAST_TFTP

No mainline board enables CONFIG_MCAST_TFTP and there have been
compilation issues with the code for some time. Additionally, it has a
potential buffer underrun issue (reported as a side note in
CVE-2018-18439).

Remove the multicast TFTP code but keep the driver API for the future
addition of IPv6.

Cc: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
Signed-off-by: Chris Packham <judge.packham@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/include/net.h b/include/net.h
index 359bfb5..dd52ed3 100644
--- a/include/net.h
+++ b/include/net.h
@@ -140,9 +140,7 @@
 	int (*recv)(struct udevice *dev, int flags, uchar **packetp);
 	int (*free_pkt)(struct udevice *dev, uchar *packet, int length);
 	void (*stop)(struct udevice *dev);
-#ifdef CONFIG_MCAST_TFTP
 	int (*mcast)(struct udevice *dev, const u8 *enetaddr, int join);
-#endif
 	int (*write_hwaddr)(struct udevice *dev);
 	int (*read_rom_hwaddr)(struct udevice *dev);
 };
@@ -175,9 +173,7 @@
 	int (*send)(struct eth_device *, void *packet, int length);
 	int (*recv)(struct eth_device *);
 	void (*halt)(struct eth_device *);
-#ifdef CONFIG_MCAST_TFTP
-	int (*mcast)(struct eth_device *, const u8 *enetaddr, u8 set);
-#endif
+	int (*mcast)(struct eth_device *, const u8 *enetaddr, int join);
 	int (*write_hwaddr)(struct eth_device *);
 	struct eth_device *next;
 	int index;
@@ -286,11 +282,7 @@
 int eth_rx(void);			/* Check for received packets */
 void eth_halt(void);			/* stop SCC */
 const char *eth_get_name(void);		/* get name of current device */
-
-#ifdef CONFIG_MCAST_TFTP
 int eth_mcast_join(struct in_addr mcast_addr, int join);
-#endif
-
 
 /**********************************************************************/
 /*
@@ -577,10 +569,6 @@
 extern int net_ntp_time_offset;			/* offset time from UTC */
 #endif
 
-#if defined(CONFIG_MCAST_TFTP)
-extern struct in_addr net_mcast_addr;
-#endif
-
 /* Initialize the network adapter */
 void net_init(void);
 int net_loop(enum proto_t);