[Cin] OpenCL again

[Andrea paz]

> may be surround first hwupload in ",format=p010" just like output part does?
By removing both "format=" or removing one and leaving the other I
always get format error.

Using bt2020 as a transfer instead of bt709 the GPU occupancy is 100%
but it actually stands still without proceeding with rendering. I have
to kill the process.

I have tried making a few .opts files, but they don't work for me
(they are ignored without any message, not even error!). Could you
provide me with one because I think I am doing it wrong.