Revert "e_client: Revert unintended change"

Revert "e_client: Revert unintended change"

This reverts commit cd2c7bed010b6dff41e5057e61cd024781b45edb.

An unintended change was made mistakenly from the commit:

commit 790fee54df0cead13ff0c17c7fd21c2ddae6302d (HEAD)
Author: Seunghun Lee <shiin.lee@samsung.com>
Date:   Wed Jun 23 10:53:24 2021 +0900

    subsurface: Add a function for getting parent of sub-surface

Actually this had been corrected from the commit 760ee67 by chance,
but I made the commit cd2c7be because I misunderstood it.

Change-Id: Id25abf493a280696f977dbf5dfef1b4ed199166b