Refer to "Advanced SIMD two registers misc", ARM DDI 0487F.b F4-4228.

Also moved the method down to the section with all the NEON
instructions, matching where the declaration in assembler-arm.h is.

Bug: v8:10553
Change-Id: I450edbfc3eafead4aad419299c93e43bd9d83133
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2252764Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68442}