MIPS: ath79: Handle more MISC IRQs

The AR724X SoCs have more IRQ sources hooked into the MISC IRQ controller.
The patch adds support for them.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2440/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>