drm/amd/display: Check if PSR enabled when entering MALL

drm/amd/display: Check if PSR enabled when entering MALL

[Description]
- When attempting to enter MALL SS when a PSR panel
  is connected, we have to check that the PSR panel
  has already entered PSR because the vsync interrupt
  call is per display index (can be called for the
  non-PSR panel first)
- Also don't override link settings when programming
  phantom stream (main and phantom pipe share the same link)

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Brian Chang <Brian.Chang@amd.com>
Signed-off-by: Alvin Lee <Alvin.Lee2@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>