agp/intel: Respect the GTT size on Sandybridge for scratch page setup.

This is similar to 14bc490bbdf1b194ad1f5f3d2a0a27edfdf78986 which
respected it for how much of the GTT we would actually use.  Now we
won't clear beyond allocated memory when filling the GTT with scratch
page addresses.

Signed-off-by: Eric Anholt <eric@anholt.net>
1 file changed