rnndb/nv50/clock: "Nail down" HOST_CLK selector

Signed-off-by: Roy Spliet <r.spliet@student.tudelft.nl>
rnndb/nv50/clock: Add PDISP clock switch

Signed-off-by: Roy Spliet <r.spliet@student.tudelft.nl>
Merge branch 'master' of ssh://git.code.sf.net/p/nouveau/envytools