panfrost: Use ralloc() to allocate instructions to avoid leaking those objs

panfrost: Use ralloc() to allocate instructions to avoid leaking those objs

Instructions attached to blocks are never explicitly freed. Let's
use ralloc() to attach those objects to the compiler context so that
they are automatically freed when the ctx object is freed.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>