dt-bindings: net: sparx5: Narrow properly LAN969x register space windows

Commit 267bca00 ("dt-bindings: net: sparx5: correct LAN969x register
space windows") said that LAN969x has exactly two address spaces ("reg"
property) but implemented it as 2 or more.  Narrow the constraint to
properly express that only two items are allowed, which also matches
Linux driver.

Fixes: 267bca00 ("dt-bindings: net: sparx5: correct LAN969x register space windows")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20251026101741.20507-2-krzysztof.kozlowski@linaro.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>