Revert "bpf, sockmap: Convert schedule_work into delayed_work"

This reverts commit 657cfb19 which is
commit 29173d07 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: I0ba69fdcb3ad9ecccf1bfb1070d3862b8cc2d3b4
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>