liveupdate: kho_block: include linux/mm.h for virt/phys translation

kho_block.c 增加 #include <linux/mm.h>；CONFIG_KFENCE 下 virt_to_phys/phys_to_virt 展开需 offset_in_page/page_address 声明，否则 LoongArch 编译失败。