intel: Fix Y tiling support for glCopyTexSubImage's alpha override.

Apparently we don't have any piglit tests for this, because it would have
assertion failed in a debug build, or just rendered wrong in a non-debug
build if the destination wasn't covering whole tiles.

v2: Use the new macros.

Reviewed-by: Paul Berry <stereotype441@gmail.com> (v1)
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org> (v1)
1 file changed