drm/amd/display: move dc_link functions in protocols folder to dc_link_exports

[why]
link component should only have one interface serving dc.

[how]
We are moving dc_link functions exposed to DM to dc_link_exports
and unify link component interface in link.h with function pointer
to match the style of other dc component. This is the third step to move
dc_link functions under protocols folder to dc_link_exports.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: break down dc_link.c

[why]
dc_link contains over 30k line of code, the decision is to break it
down to files residing in link folder based on functionality. This
change is the last break down change which will remove dc_link.c
file after everything is broken down.

[how]
Move remaining dc_link.c functions into link_detection, link_dpms,
link_validation, link_resource, and link_fpga and remove dc_link.

Reviewed-by: George Shen <George.Shen@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: move dp irq handler functions from dc_link_dp to link_dp_irq_handler

Create new files link_dp_irq_handler.c and link_dp_irq_handler.h, and
move DP irq handler functions into them.

Reviewed-by: George Shen <George.Shen@amd.com>
Acked-by: Alan Liu <HaoPing.Liu@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>