Revert "drm/amd/display: Exit idle optimizations before attempt to access PHY"

This reverts commit de612738.

Reason to revert: screen flashes or gray screen appeared half of the
screen after resume from S4/S5.

Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Signed-off-by: Brandon Syu <Brandon.Syu@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>