MIPS: ATH79: Set missing irq ack handler for ar7100-misc-intc irq chip

MIPS: ATH79: Set missing irq ack handler for ar7100-misc-intc irq chip

The irq ack handler was forgotten while introducing OF support.
Only ar71xx and ar933x based devices require it.

Signed-off-by: Alexander Couzens <[email protected]>
Acked-by: Alban Bedel <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: Rob Herring <[email protected]>
Cc: Pawel Moll <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Ian Campbell <[email protected]>
Cc: Kumar Gala <[email protected]>
Cc: [email protected]
Cc: Jason Cooper <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: [email protected]
Patchwork: https://patchwork.linux-mips.org/patch/11163/
Signed-off-by: Ralf Baechle <[email protected]>