dt-bindings: arm: samsung: document Klimt WiFi board binding

Add binding for Galaxy Tab S 8.4", based on Exynos 5420 with codename
klimt-wifi.

Signed-off-by: Henrik Grimler <henrik@grimler.se>
Link: https://lore.kernel.org/r/20220124131241.29946-2-henrik@grimler.se


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>