media: iris: Fix opp scaling of power domains

Pass PD_FLAG_REQUIRED_OPP flag to allow opp framework to scale the rpmpd
power domains.

Signed-off-by: Akhil P Oommen <akhilpo@oss.qualcomm.com>
Reviewed-by: Dikshita Agarwal <quic_dikshita@quicinc.com>
Signed-off-by: Bryan O'Donoghue <bod@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>