drm/amd/display: Wait for double buffer update on ODM changes

[WHAT & HOW]
We must wait for ODM double buffer updates to complete
before exiting the pipe update sequence or we may reduce
DISPCLK and hit some transient underflow (pixel rate is
reduced before the pipes have ODM enabled).

Reviewed-by: Samson Tam <samson.tam@amd.com>
Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alvin Lee <alvin.lee2@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>