drm/amd/display: add missing code change init pix_per_cycle

[why]
missing change when port to these two dcn version.

Reviewed-by: Chris Park <Chris.Park@amd.com>
Reviewed-by: Leo Ma <hanghong.ma@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Charlene Liu <Charlene.Liu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>