drm/nouveau/clk/gk20a: abstract pl_to_div

pl_to_div may be done differently depending on the chip. Abstract this
operation so the same logic can be reused for them as well.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
1 file changed