cmd/internal, cmd/link: unify the relocation naming style of loong64

cmd/internal, cmd/link: unify the relocation naming style of loong64

Change-Id: I2990701e71a63af7bdd6851b6008dc63cb1c1a83
Reviewed-on: https://go-review.googlesource.com/c/go/+/535616
Reviewed-by: abner chenc <chenguoqi@loongson.cn>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: sophie zhao <zhaoxiaolin@loongson.cn>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>