drm/amd/display: Fix overlay validation by considering cursors

A few weeks ago, we saw a two cursor issue in a ChromeOS system. We
fixed it in the commit:

 drm/amd/display: Fix two cursor duplication when using overlay
 (read the commit message for more details)

After this change, we noticed that some IGT subtests related to
kms_plane and kms_plane_scaling started to fail. After investigating
this issue, we noticed that all subtests that fail have a primary plane
covering the overlay plane, which is currently rejected by amdgpu dm.
Fail those IGT tests highlight that our verification was too broad and
compromises the overlay usage in our drive. This patch fixes this issue
by ensuring that we only reject commits where the primary plane is not
fully covered by the overlay when the cursor hardware is enabled. With
this fix, all IGT tests start to pass again, which means our overlay
support works as expected.

Cc: Tianci.Yin <tianci.yin@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Nicholas Choi <nicholas.choi@amd.com>
Cc: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Cc: Mark Yacoub <markyacoub@google.com>
Cc: Daniel Wheeler <daniel.wheeler@amd.com>

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>