!880 LoongArch: kdump: Add high memory reservation

Merge Pull Request from: @Hongchen_Zhang 
 
kdump function test failed on 3C5000+7A2000 dual-bridge machine,
we fix it as following:
reserve high memory for the capture kernel to avoid kdump operation
failure on 3C5000 machines with old firmware.

after apply this patch,the following test case passed:
1) add crashkernel=512M in commandline 
2) systemctl start kdump
3) echo c >/proc/sysrq-trigger
4) after reboot, vmcore file created in /var/crash directory
 
 
Link:https://gitee.com/openeuler/kernel/pulls/880

 

Reviewed-by: Jialin Zhang <zhangjialin11@huawei.com>
Reviewed-by: Guo Dongtai <guodongtai@kylinos.cn>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>