ARM: dts: qcom-pm8841: add interrupt controller properties

Now that the pmic-mpp is a proper hierarchical IRQ chip, add interrupt
controller properties ('interrupt-controller' and '#interrupt-cells').
The interrupts property is no longer needed so remove it.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211008012524.481877-22-dmitry.baryshkov@linaro.org
