drm/amd/display: do not wait for vblank during pipe programming

[Why]
Waiting for the vlbank every time a global sync update is requested,
including during full update flips, results in a stutter.

[How]
Do not wait for vblank during pipe programming.

Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Josip Pavic <Josip.Pavic@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>