drm/amd/display: update pipe selection policy to check head pipe

[Why]
No check on head pipe during the dml to dc hw mapping will allow illegal
pipe usage. This will result in a wrong pipe topology to cause mpcc tree
totally mess up then cause a display hang.

[How]
Avoid to use the pipe is head in all check and avoid ODM slice during
preferred pipe check.

Cc: stable@vger.kernel.org
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Yihan Zhu <Yihan.Zhu@amd.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>