Revert "bpf, sockmap: Reschedule is now done through backlog"

This reverts commit d908a8a3 which is
commit bce22552 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Iefb1b67dd7b13adcb74b867d056f5496aaf6a6c9
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>