In both PrepareCall and ProcessParameter, we were incorrectly passing
the reg code of a Q register into LiftoffRegister::ForFpPair, which
takes a D register. Similar to the F32 case (the reg code was halved),
the reg code needs to be doubled (q1 -> d2) before constructing the
LiftoffRegister.

Bug: v8:9909
Change-Id: Id4df9e99b92546f68be0d99d98f0a1ac25ee7e5c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2013492Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65925}