Compiling an irqchip driver as a platform driver needs to bunch of
things to be done right:
- Making sure the parent domain is initialized first
- Making sure the device can't be unbound from sysfs
- Disallowing module unload if it's built as a module
- Finding the parent node
- Etc.

Instead of trying to make sure all future irqchip platform drivers get
this right, provide boilerplate macros that take care of all of this.

An example use would look something like this. Where acme_foo_init and
acme_bar_init are similar to what would be passed to IRQCHIP_DECLARE.

IRQCHIP_PLATFORM_DRIVER_BEGIN(acme_irq)
IRQCHIP_MATCH("acme,foo", acme_foo_init)
IRQCHIP_MATCH("acme,bar", acme_bar_init)
IRQCHIP_PLATFORM_DRIVER_END(acme_irq)
Signed-off-by: Saravana Kannan <saravanak@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: https://lore.kernel.org/r/20200718000637.3632841-2-saravanak@google.com