anv/image: Get rid of the memset(aux, 0, sizeof(aux)) hack

anv/image: Get rid of the memset(aux, 0, sizeof(aux)) hack

Up until now, we've been memsetting the auxiliary surface to 0 at
BindImageMemory time to ensure that it is properly initialized.
However, this isn't correct because apps are allowed to freely alias
memory between different images and buffers so long as they properly
track whether or not a particular image is valid and, if it isn't,
transition from UNINITIALIZED to something else before using it.  We
now implement those transitions so we can drop the hack.

Reviewed-by: Nanley Chery <nanley.g.chery@intel.com>
Cc: "17.1" <mesa-stable@lists.freedesktop.org>