media: camss: vfe: Reserve VFE lines on stream start and link to CSID

media: camss: vfe: Reserve VFE lines on stream start and link to CSID

For multiple virtual channels support, each VFE line can be in either
ON, RESERVED or OFF states. This allows the starting and stopping
of a VFE line independently of other active VFE lines (e.g. already-
running lines stay in ON state, and newly-added lines are RESERVED)

Also, link the CSID entity's source ports to corresponding VFE lines.

Signed-off-by: Milen Mitkov <quic_mmitkov@quicinc.com>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Tested-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Acked-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>