drm/amd/display: fix linux dp link lost handled only one time

[Why]
linux amdgpu defer handle link lost irq. dm add handle
request to irq work queue for the first irq of link lost.
if link training fails for link lost handle, link will not
be enabled anymore.

[How]
allow adding handle request of link lost to work queue
before running dp link training for link lost.

Signed-off-by: Hersen Wu <hersenxs.wu@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>