drm/amd/display: Increase stutter watermark for dcn303

[Why&How]
Hardware team suggested to use SRExitTime= 35.5us as w/a to prevent
underflow in certain modes.

Reviewed-by: Martin Leung <martin.leung@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Bing Guo <bing.guo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>