Workaround for now to avoid underflow.

The uclk switch time should really be bumped up to 404, but doing so
would expose p-state hang issues for higher bandwidth display
configurations.
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>