Loongarch: Support loongarch avec

Introduce the advanced extended interrupt controllers. This feature will
allow each core to have 256 independent interrupt vectors and MSI
interrupts can be independently routed to any vector on any CPU.

[ tglx: Fixed up coding style. Made on/offline functions void ]

Co-developed-by: Jianmin Lv <lvjianmin@loongson.cn>
Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
Co-developed-by: Liupu Wang <wangliupu@loongson.cn>
Signed-off-by: Liupu Wang <wangliupu@loongson.cn>
Signed-off-by: Tianyang Zhang <zhangtianyang@loongson.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240604125026.18745-1-zhangtianyang@loongson.cn