drm/amd/display: Fix static screen event mask definition change

[why]
The static screen event mask definition is different
betwnn DCN31 after and before.

[how]
Rename DCN30_set_static_screen_control to DCN31.

Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Yiling Chen <yi-ling.chen2@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>