intel: Make intel_region's pitch be bytes instead of pixels.

intel: Make intel_region's pitch be bytes instead of pixels.

We almost never want a stride in pixels -- if you're doing anything with
a stride, you're specifying an offset or incrementing a pointer, and in
both cases you had to multiply by cpp to get the bytes value you wanted.
But worse, on the way to creating a region from a new tiled BO, we
divided by cpp to get pitch in pixels, and for an RGB32 buffer (an
upcoming change) the pitch wouldn't divide exactly, and we'd end up with
a wrong stride in our region.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>