uboot-imx

linux/if_ether.h: Initial import from Linux kernel v4.17

This imports include/uapi/linux/if_ether.h from Linux kernel v4.17.
It can be very helpful When porting Linux ethernet driver to U-Boot.

Note it is not exactly the same as the kernel one, as checkpatch
issues are fixed.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>