dev_init_scheduler() and dev_activate() expect the caller to
hold RTNL. Since we don't want blackhole device to be initialized
per ns, we are initializing at init.
Fixes: f38e56a2e18 ("loopback: create blackhole net device similar to loopack.") Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Mahesh Bandewar <maheshb@google.com> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: David S. Miller <davem@davemloft.net>