colorspace: add Dolby Vision Profile 5 (IPT-PQ)

Note that these matrix coefficients are technically signalled in the RPU
structs, but the values appear to never change (and the values used in
practice match the values from the patent WO 2016/172091 A1 exactly), so
I'm tentatively hard-coding this for the time being. (And because custom
matrix support would be very annoying to implement, API-wise)

Partially implements #113