drm/amd/display: merge dc_link.h into dc.h and dc_types.h

drm/amd/display: merge dc_link.h into dc.h and dc_types.h

[ Upstream commit 7ae1dbe6547c39410d82156c96eaa9c8cf55e87a ]

[why]
Remove the need to include dc_link.h separately. dc.h should contain
everything needed on DM side.

[How]
Merge dc_link.h into dc.h and dc_types.h so DM only needs to include
dc.h to use all link public functions.

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>
Stable-dep-of: eeefe7c4820b ("drm/amd/display: hpd rx irq not working with eDP interface")
Signed-off-by: Sasha Levin <sashal@kernel.org>