freedreno: add helper to uncompress UBWC resource

freedreno: add helper to uncompress UBWC resource

We'll need this for a few edge cases, like image/sampler view that uses
a format that UBWC does not support with a resource originally created
in a format that UBWC does support.

NOTE we *could* in some cases do an in-place uncompress.  But that has
a couple potential sharp edges:

 1) the uncompressed buffer could have different layout, ie. a5xx
    with meta and pixel data of layers/levels interleaved.

 2) if it comes mid-batch, it would force flush, or somehow fixing
    up cmdstream for draws already emitted.  But with the resource
    shadowing approach we can rely on batch re-ordering to avoid
    splitting things.. older draws see the older compressed version,
    newer draws see the new uncompressed version of the rsc.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>