Revert "net: rtnetlink: add bulk delete support flag"

This reverts commit 2b0d1dc3 which is
commit a6cec0bc 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: I8cc1e6be45fdc9d34a8cd5972d5e3a16a94a9825
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>