cmd/compile: fix the implementation of NORconst on loong64
In the loong64 instruction set, there is no NORI instruction,
so the immediate value in NORconst need to be stored in register
and then use the three-register NOR instruction.
Change-Id: I5ef697450619317218cb3ef47fc07e238bdc2139
Reviewed-on: https://go-review.googlesource.com/c/go/+/673836 Reviewed-by: abner chenc <chenguoqi@loongson.cn> Reviewed-by: David Chase <drchase@google.com> Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>