!1511 config: riscv64: Add initial openeuler_defconfig

Merge Pull Request from: @xingmz 
 
This config is based on riscv64-config.all.final of
https://gitee.com/openeuler-risc-v/kernel.git
openEuler-22.03-LTS-SP2:5.10.0-153.1.0.80, generated by 'make olddefconfig',
merged configs tested in kernel v6.1.19,
and cleanup compiler's indicators. 
 
Link:https://gitee.com/openeuler/kernel/pulls/1511 

Reviewed-by: Zhang Xuzhou <zhangxuzhou4@huawei.com> 
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> 
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>