freedreno: Check cb0 in rebind_resource()

freedreno: Check cb0 in rebind_resource()

Previously we were expecting cb0 to be user_buffer.  (We did in some
cases upload it to a gpu buffer, but this was an internally allocated
buffer and not something subject to rebind.)  But with TC it becomes
a gpu buffer.

(Technically, with pctx->const_uploader, we shouldn't hit the rebind
path for cb0, but better to not try to be overly clever.. sooner or
later that would bite us.)

Signed-off-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9323>