drm/amdgpu: remove distinction between explicit and implicit sync (v2)

According to Marek a pipeline sync should be inserted for implicit syncs well.

v2: bump the driver version

Signed-off-by: Christian König <christian.koenig@amd.com>
Tested-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>