kernel: backport ifconfig ioctl support for class e addresses

kernel: backport ifconfig ioctl support for class e addresses

Backport net: Allow class-e address assignment via ifconfig ioctl
While most distributions long ago switched to the iproute2 suite
of utilities, which allow class-e (240.0.0.0/4) address assignment,
distributions relying on busybox, toybox and other forms of
ifconfig cannot assign class-e addresses without this kernel patch.

While CIDR has been obsolete for 2 decades, and a survey of all the
open source code in the world shows the IN_whatever macros are also
obsolete... rather than obsolete CIDR from this ioctl entirely, this
patch merely enables class-e assignment, sanely.

https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=65cab850f0eeaa9180bd2e10a231964f33743edf

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>