isl: Rename s/lod_align/image_align/ for consistency

isl: Rename s/lod_align/image_align/ for consistency

Regarding the subimages within a surface, sometimes isl called them
"images" and sometimes "LODs". This patch make isl consistently refer to
them as "images".  I choose the term "image" over "LOD" because LOD is
an misnomer when applied to 3D surfaces. The alignment applies to each
individual 2D subimage, not to the LOD as a whole.

This patch changes no behavior. It's just a manually performed,
case-insensitive, replacement s/lod/image/ that maintains correct
indentation.  any behavior.