drm/amd/display: Fix FRL assertion on boot

[why]
Make sure to ungate the clocks on boot
so programming sequence is done successfully.

[how]
Move the ungate logic after bios init.

Reviewed-by: Xi (Alex) Liu <xi.liu@amd.com>
Acked-by: Hersen Wu <hersenxs.wu@amd.com>
Signed-off-by: Sung Joon Kim <sungkim@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>