Revert "Add a reference to ucounts for each cred"

This reverts commit b2c4d9a3.

It breaks the abi and is not needed on Android kernels.

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I295a6c8088e4297400c1feebd78abd2f6c5edd7e