drm/amd/display: Check that hw cursor is not required when falling back to subvp sw cursor

[WHY]
When using a sw cursor and flip immediate, the plane that is flipping
immediately will do partial updates causing tearing.
When on certain displays, subvp is expected based on
timings but should be disabled in specific use cases that are not
accounted for.

[HOW]
This was fixed by improving the timings check by using the hw cursor
required flag to cover the unaccounted use cases.

Reviewed-by: Austin Zheng <austin.zheng@amd.com>
Signed-off-by: Peterson <peterson.guo@amd.com>
Signed-off-by: Fangzhi Zuo <jerry.zuo@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>