drm/amd/display: revert "Reset fifo after enable otg"

[Why]
This change causes regression, that prevents some systems
from lighting up internal displays.

[How]
Revert this patch until a new solution is ready.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Zhan Liu <Zhan.Liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>