ARM: imx: avic: Convert to using IRQCHIP_DECLARE

Using IRQCHIP_DECLARE lets fw_devlink know that it should not wait for
these interrupt controllers to be populated as struct devices. Without
this change, fw_devlink=on will make the consumers of these interrupt
controllers wait for the struct device to be added and thereby block the
consumers' probes forever. Converting to IRQCHIP_DECLARE addresses boot
issues on imx25 with fw_devlink=on that were reported by Martin.

This also removes a lot of boilerplate code.

Fixes: e5904747 ("driver core: Set fw_devlink=on by default")
Reported-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Tested-by: Martin Kaiser <martin@kaiser.cx>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>