Revert "wait: Return number of exclusive waiters awaken"

This reverts commit d710b1e9.

It breaks the ABI right now, but will be brought back at the next ABI
break as it will be needed for Android systems.

Bug: 161946584
Change-Id: I1dcf1f311ce25059466d000543b020fb33d237b4
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>