cmd/internal/obj/loong64: return an error when getting address of tls variable

cmd/internal/obj/loong64: return an error when getting address of tls variable

The tls variable is thread local variable, an operation to get its address
is not supported, so we should return an error here.

Change-Id: Ia6a637f549cb886fdb643bdc04eeb269849d1096
Reviewed-on: https://go-review.googlesource.com/c/go/+/565621
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Qiqi Huang <huangqiqi@loongson.cn>
Reviewed-by: abner chenc <chenguoqi@loongson.cn>
Reviewed-by: sophie zhao <zhaoxiaolin@loongson.cn>