storage: simplify ApplyDiff() in overlay driver

It is not clear to me when it will hit the code path there, by normal
layer creation we always pass a valid parent so this branch is never
reached AFAICT.

Let's remove it and see if all tests still pass in podman, buildah and
others...

Signed-off-by: Paul Holzinger <[email protected]>

Author: Luap99

storage/drivers/overlay/overlay.go

@@ -2371,16 +2371,6 @@ func (d *Driver) DifferTarget(id string) (string, error) {
 
 // ApplyDiff applies the new layer into a root
 func (d *Driver) ApplyDiff(id, parent string, options graphdriver.ApplyDiffOpts) (size int64, err error) {
-	if !d.isParent(id, parent) {
-		if d.options.ignoreChownErrors {
-			options.IgnoreChownErrors = d.options.ignoreChownErrors
-		}
-		if d.options.forceMask != nil {
-			options.ForceMask = d.options.forceMask
-		}
-		return d.naiveDiff.ApplyDiff(id, parent, options)
-	}
-
 	idMappings := options.Mappings
 	if idMappings == nil {
 		idMappings = &idtools.IDMappings{}