dt-bindings: Drop Beniamin Bia and Stefan Popa

Emails to Beniamin Bia and Stefan Popa bounce ("550 5.1.10
RESOLVER.ADR.RecipientNotFound; Recipient not found by SMTP address
lookup").

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220809162752.10186-4-krzysztof.kozlowski@linaro.org