net: Hide more code behind CONFIG_CMD_TFTPPUT

This commit reduces code size a little by making the ICMP handler only
available to tftpput. This is reasonable since it is the only user at
present (ping just uses the normal handler).

Signed-off-by: Simon Glass <sjg@chromium.org>

net/tftp.c

diff --git a/net/tftp.c b/net/tftp.c
index 961fdd1..e34f202 100644
--- a/net/tftp.c
+++ b/net/tftp.c
@@ -421,7 +421,7 @@
 			 TftpOurPort, len);
 }
 
-
+#ifdef CONFIG_CMD_TFTPPUT
 static void icmp_handler(unsigned type, unsigned code, unsigned dest,
 			 IPaddr_t sip, unsigned src, uchar *pkt, unsigned len)
 {
@@ -430,6 +430,7 @@
 		restart("TFTP server died");
 	}
 }
+#endif
 
 static void
 TftpHandler(uchar *pkt, unsigned dest, IPaddr_t sip, unsigned src,
@@ -771,8 +772,9 @@
 
 	NetSetTimeout(TftpTimeoutMSecs, TftpTimeout);
 	NetSetHandler(TftpHandler);
+#ifdef CONFIG_CMD_TFTPPUT
 	net_set_icmp_handler(icmp_handler);
-
+#endif
 	TftpRemotePort = WELL_KNOWN_PORT;
 	TftpTimeoutCount = 0;
 	/* Use a pseudo-random port unless a specific port is set */