i965: Use helper function intel_get_tile_dims() in surface setup

It takes care of using the correct tile width if we later use other
tiling patterns for aux miptree.

V2: Remove the comment about using Yf for aux miptree.

Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Chad Versace <chad.versace@intel.com>
1 file changed