drm/amd/display: calculate the remain segments for all pipes

[WHY]
In some cases the remain de-tile buffer segments will be greater
than zero if we don't add the non-top pipe to calculate, at
this time the override de-tile buffer size will be valid and used.
But it makes the de-tile buffer segments used finally for all of pipes
exceed the maximum.

[HOW]
Add the non-top pipe to calculate the remain de-tile buffer segments.
Don't set override size to use the average according to pipe count
if the value exceed the maximum.

Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Signed-off-by: Zhikai Zhai <zhikai.zhai@amd.com>
Signed-off-by: Tom Chung <chiahsuan.chung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>