irqchip/loongson: Fix syscore ops registration

LoongArch inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6ONTH



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In irq-loongson-eiointc and irq-loongson-pch-pic, syscore
ops is registrated two times, which will break the syscore
ops list.

Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
Change-Id: I87d4af80afbe5397c25a8d799e844528650c9e2c