LoongArch: Add identifier names to arguments of die() declaration

Add identifier names to arguments of die() declaration in ptrace.h
to fix the following checkpatch warnings:

  WARNING: function definition argument 'const char *' should also have an identifier name
  WARNING: function definition argument 'struct pt_regs *' should also have an identifier name

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