!476 LoongArch: fix failed to boot

Merge Pull Request from: @Hongchen_Zhang 
 
1. commit ad404010 ("entry: Add support for TIF_NOTIFY_SIGNAL")
changed the signal handler name to arch_do_signal_or_restart,so
change the signal handler name for LoongArch too.
2. fix virtual machine startup error
3. fix failed boot when using old firmware 

After apply this PR,the following test case passed:
  - boot Loongson-3C5000LL+7A1000 machine with firmware
     Loongson-UDK2018-V2.0.04163-beta6
  - success boot to login
 
 
Link:https://gitee.com/openeuler/kernel/pulls/476

 

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