LoongArch: Move three functions from kprobes.c to inst.c

The three functions insns_not_supported(), insns_need_simulation() and
arch_simulate_insn() will be used for uprobes, move them from kprobes.c
to inst.c, this is preparation for later patch, no functionality change.

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