bifrost: Add support for nir_op_imul

Unfortunately this doesn't map nicely to the existing instruction
classes, so we'll make a new one for now.

Signed-off-by: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6091>
6 files changed