drm/amdgpu: switch DM to atomic fence helpers v2

This gives us the standard atomic implicit and explicit fencing rules.

v2: move the wait to amdgpu_dm_atomic_commit_tail

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Cc: Roman Li <Roman.Li@amd.com>
Cc: Qingqing Zhuo <qingqing.zhuo@amd.com>
Cc: Jude Shih <shenshih@amd.com>
Cc: Wayne Lin <Wayne.Lin@amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220509074712.163899-1-christian.koenig@amd.com