LoongArch: Adjust arch_do_signal_or_restart() to adapt generic entry

Commit 8ba62d37 ("task_work: Call tracehook_notify_signal from
get_signal on all architectures") adjust arch_do_signal_or_restart() for
all architectures. LoongArch hasn't been upstream yet at that time and
can be still built successfully without adjustment because this function
has a weak version with the correct prototype. It is obviously that we
should convert LoongArch to use new API, otherwise some signal handlings
will be lost.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>