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

This reverts commit 1e4e379c.

It breaks the Android KABI and will be brought back at a later time when
it is safe to do so.

Bug: 161946584
Change-Id: I046885f1246a0def7ee238f833ee78ba8a4cecb0
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>