LoongArch: Remove five DIE_* definitions in kdebug.h

For now, DIE_PAGE_FAULT, DIE_BREAK, DIE_SSTEPBP, DIE_UPROBE and
DIE_UPROBE_XOL are not used by any code, remove them.

Tested-by: Jeff Xie <xiehuan09@gmail.com>
Suggested-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>