drm/radeon/kms: use wait queue (events) for VBLANK sync

This already simplifies code significally and makes it maintaible
in case of adding memory reclocking plus voltage changing in future.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
6 files changed