dt-bindings: arm: qcom: switch maintainer to Bjorn

Emails to Stephen bounce since long time ("Recipient address rejected:
undeliverable address: No such user here."), so change maintainer to
Qualcomm platform maintainer.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220520124018.367004-1-krzysztof.kozlowski@linaro.org