drm/amd/display: Preserve original aspect ratio in create stream

[Why]
The original picture aspect ratio in mode struct may have chance be
overwritten with wrong aspect ratio data in create_stream_for_sink().
It will create a different VIC output and cause HDMI compliance test
failed.

[How]
Preserve the original picture aspect ratio data during create the
stream.

Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Tom Chung <chiahsuan.chung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>