accel/amdxdna: Fix use-after-free in debug BO command handling

accel/amdxdna: Fix use-after-free in debug BO command handling

When a debug BO command completes, job->drv_cmd may already have been
freed. Accessing it from aie2_sched_drvcmd_resp_handler() can result in
a use-after-free and memory corruption.

Fix this by introducing reference counting for drv_cmd objects and
transferring ownership to the job while it is in flight. This ensures
that the command remains valid until the completion handler finishes
processing it.

Fixes: 7ea046838021 ("accel/amdxdna: Support firmware debug buffer")
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Link: https://patch.msgid.link/20260701155556.663541-1-lizhi.hou@amd.com