ARM: dts: qcom: msm8974: align WCNSS Bluetooth node name with bindings

Bindings expect WCNSS Bluetooth child to be named "bluetooth":

  remoteproc@fb204000: smd-edge:wcnss: 'bt' does not match any of the regexes: 'pinctrl-[0-9]+'

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230421195437.31513-1-krzysztof.kozlowski@linaro.org