net: Convert CONFIG_IP_DEFRAG to Kconfig

Convert CONFIG_IP_DEFRAG to Kconfig, update defconfigs, headers
and whitelist. This patch is a follow-up on a patch by Christian
Gmeiner with the added config/header/whitelist updates.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Reported-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Cc: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/configs/sandbox64_defconfig b/configs/sandbox64_defconfig
index 1bc3bd3..bfb1eaf 100644
--- a/configs/sandbox64_defconfig
+++ b/configs/sandbox64_defconfig
@@ -74,6 +74,7 @@
 CONFIG_OF_HOSTFILE=y
 CONFIG_DEFAULT_DEVICE_TREE="sandbox64"
 CONFIG_NETCONSOLE=y
+CONFIG_IP_DEFRAG=y
 CONFIG_REGMAP=y
 CONFIG_SYSCON=y
 CONFIG_DEVRES=y