[media] st-hva: potential null pointer dereference in hva_hw_its_irq_thread()

[Evgeny Novikov]

If ctx_id >= HVA_MAX_INSTANCES in hva_hw_its_irq_thread(), it dereferences
ctx that is initialized to NULL.

I can not provide the patch since I do not know the logic of the driver
and I have not a capability to test it.

Found by Linux Driver Verification project (linuxtesting.org).

-- 
Best regards,
Evgeny Novikov