[cleanup][dataview] Refactor some DataView methods in Torque

This CL simplifies the Torque code for DataView getters by matching
the setters implementation whenever possible.

Change-Id: I8acf9ddc7a531043abb27105b61199c91f209d27
Reviewed-on: https://chromium-review.googlesource.com/1146920Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Théotime Grohens <theotime@google.com>
Cr-Commit-Position: refs/heads/master@{#54634}