Revert "padata: add separate cpuhp node for CPUHP_PADATA_DEAD"

This reverts commit d6c434ae which is
commit 93175d93 upstream.

It breaks the Android kernel abi and is not needed in this branch at
this point in time.

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I53f15ad34f2124aa7a4e06dafcdb828666a91278