Revert "ANDROID: PM / Domains: add vendor_hook to disallow domain idle state"

This reverts commit e1148714.

The hook is not used by any vendor, so remove it to help with merge
issues with future LTS releases.

If this is needed by any real user, it can easily be reverted to add it
back and then the symbol should be added to the abi list at the same
time to prevent it from being removed again later.

Bug: 203756332
Bug: 175718935
Bug: 195914333
Cc: Lina Iyer <ilina@codeaurora.org>
Cc: Maulik Shah <mkshah@codeaurora.org>
Change-Id: I08363a267e09826f11380efec1ee5a76a4eb7f75
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>