wcn36xx: Split mmio space into explicit regions

Split the wcnss mmio space into explicit regions for ccu and dxe and
acquire these from the node referenced by the qcom,mmio phandle.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>