i965: Reset miptree aux state on update_image_buffer

i965: Reset miptree aux state on update_image_buffer

When we get a miptree in through glxBindImageEXT, we don't know the
current aux state so we have to assume the worst-case.  If the image
gets recreated, everything is fine because miptreecreate_for_dri_image
sets it to the default.  However, if our miptree is recycled, then we
may have stale aux_usage and we need to reset to the default otherwise
our aux_state tracking will get messed up.

Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Chad Versace <chadversary@chromium.org>