There is a typo getting the values of the lanes, only on big-endian
systems. (On little-endian systems, the use of LANE macro hides the
error).

Bug: v8:11008
Change-Id: I99efde506dab443efd336346ec920fcd957daae2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2486614Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70666}