drm/amd/display: Request PHYCLK adjustment on PHY enable/disable

[Why]
Currently we don't explicitly send a request for a minimum PHYCLK, and
we hope that the dependencies other clocks have will raise PHYCLK when
needed.

[How]
- new clk_mgr function to keep track of PHYCLK requirements
- request maximum requirement across all links
- remove PHYCLK from clock state comparator, as it doesn't come from DML

Signed-off-by: Joshua Aberback <joshua.aberback@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>