soc: qcom: smsm: Implement support for get_irqchip_state

soc: qcom: smsm: Implement support for get_irqchip_state

At the moment there is no way for drivers to get the current state
of the interrupt signal reported by a remote processor. The irqchip
API has generic functionality for this, using irq_get_irqchip_state().

Implement support for getting the IRQCHIP_STATE_LINE_LEVEL by reading
the remote state and checking the bit for the specified IRQ.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20210712135703.324748-1-stephan@gerhold.net
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>