This is the same cleanup as in the previous CL, but for {EmitBinOpImm}.
This requires a minor change in the name of the emit functions with
immediate, to make them distinguishable from the emit functions with two
registers. We just append an "i" to the functions with immediate.

R=zhin@chromium.org

Bug: v8:10364
Change-Id: Ie3732a956698368a5f1fbe67334a13014cd2f354
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2129631
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66941}