Revert "media: cec: core: add adap_unconfigured() callback"

This reverts commit 0294e247 which is
commit 948a77aa upstream.

It breaks the Android ABI and is not needed for Android systems at this
point in time.  If needed in the future, it can come back in an abi-safe
way.

Bug: 161946584
Change-Id: I622663df8e9ddfd598285f8af7631f0406351fe0
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>