ARM: dts: ape6evm: Add NOR FLASH

Describe the 128 MiB CFI NOR FLASH, which contains the boot loader and
its environment.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>