drm/amd/display: Keep clocks high before seamless boot done

[Why]
UEFI boot usually uses a boot profile that uses higher clocks
and watermark settings.
UEFI boot surface is less optimal, for example it uses linear surface

[How]
Before we finish our seamless boot sequence, keep the clock and
watermark settings from boot.
Update to optimal settings only after first flip away from UEFI
frame buffer.

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