irqchip/loongson-eiointc: Fix irq affinity setting

In multi-node case, csr_any_send() should set EIOINTC_REG_ENABLE of
the first core of target node, not the first core of the whole.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220804025421.211958-1-chenhuacai@loongson.cn