dt-bindings: vendor-prefixes: add smartrg

SmartRG described itself as a CPE manufacturer and produced few home
network devices (e.g. wireless routers). Their SmartRG SR400ac router
(smartrg,sr400ac) is covered by in-Linux DT binding and DTS file.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240212140839.27150-1-zajec5@gmail.com


Signed-off-by: Rob Herring <robh@kernel.org>