drm/nv50-nvc0: activate/update ds channel's framebuffer on modesets
drm/nv50-nvc0: activate/update ds channel's framebuffer on modesets

The hw doesn't really appear to be designed to be used the way we have to
use it due to DRI2's design.  This leads us to having to keep the flipped
fb support active at all times.

Signed-off-by: Ben Skeggs <d9f27fb07c1e9f131223ad827fa5179f3846c30b@redhat.com>

KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs