i965: Drop mt->levels[].width/height.

i965: Drop mt->levels[].width/height.

It often confused people because it was unclear on whether it was the
physical or logical, and people needed the other one as well.  We can
recompute it trivially using the minify() macro, clarifying which value is
being used and making getting the other value obvious.

v2: Fix a pasteo in intel_blit.c's dst flip.

Reviewed-by: Chris Forbes <chrisf@ijw.co.nz> (v1)
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>