livepatch: Move 'klp_func_list' related codes out of 'arch'

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4UAQ1



--------------------------------

Move 'struct klp_func_node' into include/linux/livepatch.h,
then introduce klp_{add,del}_func_node and Move 'klp_func_list'
related codes out of 'arch' in order to reduce duplicated codes.

Preparatory only, no functional change.

Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Reviewed-by: Kuohai Xu <xukuohai@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>