iris: fix indirect draw refcnt imbalance
What does this MR do and why?
iris: fix indirect draw refcnt imbalance
Indeed, the object ring_bo was not freed.
For instance, this issue is triggered with:
"piglit/bin/arb_shader_image_load_store-host-mem-barrier -auto -fbo"
while setting GALLIUM_REFCNT_LOG=refcnt.log.
Fixes: 5438b1910464 ("iris: enable generated indirect draws")
Signed-off-by: Patrick Lerda <patrick9876@free.fr>