drm/amd/display: Fallback to SW cursor if SubVP + cursor too big

[Description]
- For SubVP cursor cannot be cached in MALL, therefore
we will switch to SW cursor if the cursor size exceeds
what can fit in the local DCN buffers (64x64x4)
- Returning false / failure for set_cursor_attributes will
fallback to SW cursor

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-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>