ARM: dts: Let Gemini NS2502 parse redboot partitions

The NS2502 uses hardcoded partitions but parsing the RedBoot
FIS should work fine, given that this flash seems to be using
0x200000 erase blocks.

Cc: Corentin Labbe <clabbe.montjoie@gmail.com>
Link: https://lore.kernel.org/r/20220412220358.3674598-1-linus.walleij@linaro.org


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>