boot/uboot: remove deprecated network settings option

It's been deprecated since the 2014.05 release, so a year has passed.
Add legacy info as well to raise a warning when it's used.

[Peter: Remove entire config.h fixup handling]
Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
diff --git a/Config.in.legacy b/Config.in.legacy
index 44de941..9b9fff0 100644
--- a/Config.in.legacy
+++ b/Config.in.legacy
@@ -105,6 +105,15 @@
 endif
 
 ###############################################################################
+comment "Legacy options removed in 2015.08"
+
+config BR2_TARGET_UBOOT_NETWORK
+	bool "U-Boot custom network settings removed"
+	select BR2_LEGACY
+	help
+	  U-Boot's custom network settings options have been removed.
+
+###############################################################################
 comment "Legacy options removed in 2015.05"
 
 config BR2_TARGET_ROOTFS_JFFS2_NANDFLASH_512_16K