buildroot

board/lego/ev3: update to 4.14 kernel and 2017.11 U-Boot

This updates the LEGO MINDSTORMS EV3 board to Linux kernel 4.14 and
U-Boot 2017.11.

* Kernel patches are dropped because they are in mainline now.
* This caused the kernel image to be >3M so some adjustments to the image
  sizes/layout needed to be made in U-Boot.
* Updated U-Boot version bumped since we are touching this config anyway

Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>