drm/amd/display: reset retimer/redriver below 340Mhz

[Description]
This is for HDMI 6Ghz mode before we load the driver, because VBIOS
not support HDMI (6Ghz mode)

Reset to redriver/retimer setting for the setting for below 340Mhz.

Signed-off-by: Charlene Liu <charlene.liu@amd.com>
Reviewed-by: Krunoslav Kovac <Krunoslav.Kovac@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>