hterm 1.22: Fix full-screen scroll region fix.

* hterm 1.19 attempted to ignore full-screen scroll regions, but the patch
  got the variable names wrong.  This fixes them.

Change-Id: I83ca631b64b1f3f6daa9e8c8546893cb83375a88
Reviewed-on: https://chromium-review.googlesource.com/177886
Reviewed-by: Marvelous Marius <mschilder@chromium.org>
Tested-by: Robert Ginda <rginda@chromium.org>