media: qcom: camss: Support RDI3 for VFE 17x

Some VFEs have four RDIs apiece. Right now the ISR code has a hard-coded
value which tops-out at RDI2 meaning only three RDIs can be utilised in
practice.

Extend out the various routines in camss-vfe-17x.c to support the higher
RDI count.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Acked-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>