Revert "net: add ndo_fdb_del_bulk"

This reverts commit 7111cc95 which is
commit 1306d536 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: I148a599c2a5b94238b0bfacd354e670dbb03f710
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>