i965/miptree: Refactor aux surface allocation

v2 (Jason): Drop unused argument in intel_alloc_aux_buffer() and
            move assignment of "buf->surf" in intel_alloc_aux_buffer()
            into this patch.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Topi Pohjolainen <topi.pohjolainen@intel.com>
1 file changed