arm64: dts: qcom: msm8996: drop unused slimbus reg-mames

Drop undocumented reg-names from slimbus node - there is only one
address range and Linux implementation does not use it.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220928152027.489543-3-krzysztof.kozlowski@linaro.org