A series of fixes for the Renesas RZG21 interrupt chip driver to prevent
spurious and misrouted interrupts.
- Ensure that posted writes are flushed in the eoi() callback
- Ensure that interrupts are masked at the chip level when the trigger
type is changed
- Clear the interrupt status register when setting up edge type trigger
modes.
- Ensure that the trigger type and routing information is set before the
interrupt is enabled.