drm/amd/display: Do not handle linkloss for eDP

[Why]
eDP is internal link and link loss is unexpected.
It is typically going to be PSR related errors, which is
handled separately.

[How]
Check for eDP and skip check for link loss

Signed-off-by: Anthony Koo <Anthony.Koo@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>