Make sure that Torque/CSA generated phi's get kRepWord32 instead
of kRepWord8 or kRepWord16, since that's how we handle small
integer values in Turbofan.

Bug: v8:7793
Change-Id: I992b43287552b6117e90fbd0e11576470bc91509
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2339096
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69253}