cmd: net: fix function name in comment

In commit 7044c6bb6 (net: cosmetic: Clean up DHCP variables and functions)
BootpCopyNetParams() was renamed to store_net_params(). Update the reference in
comment.

Cc: Joe Hershberger <joe.hershberger@ni.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>

cmd/net.c

@@ -136,7 +136,7 @@ static void netboot_update_env(void)
 	}
 #if !defined(CONFIG_BOOTP_SERVERIP)
 	/*
-	 * Only attempt to change serverip if net/bootp.c:BootpCopyNetParams()
+	 * Only attempt to change serverip if net/bootp.c:store_net_params()
 	 * could have set it
 	 */
 	if (net_server_ip.s_addr) {