Patches to go on top of Michels page_flip_target patches.

[Mario Kleiner]

Hi,

testing on "simulated" pre-DCE4 radeon hw (via setting the module
parameter radeon.use_pflipirq=0 to avoid use of pflip irqs) showed
we need some adjustments on top of Michel's page_flip_target patches
on these old asics.

Patch 2/2:

Essentially disabling the ability to flip anywhere in vblank on
pre-DCE4, either via hw programming or via software for pre-AVIVO.

Patch 1/2:

Also some small refinement i noticed was possible for that old
pageflip completion path with some functionality we added a couple
of releases ago.

So these should go into drm-next for Linux 4.9.

thanks,
-mario