!809 LoongArch: defconfig: enable memory and pci hotplug related configs for LoongArch

Merge Pull Request from: @Hongchen_Zhang 
 
enable memory and pci hotplug related configs for LoongArch,
   used by LoongArch virtual machine now. 
 
Link:https://gitee.com/openeuler/kernel/pulls/809

 

Reviewed-by: Guo Dongtai <guodongtai@kylinos.cn>
Reviewed-by: Liu Chao <liuchao173@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>