ipv4/fib: don't warn when primary address is missing if in_dev is dead

ipv4/fib: don't warn when primary address is missing if in_dev is dead

Orabug: 25308078

[ Upstream commit 391a20333b8393ef2e13014e6e59d192c5594471 ]

After commit fbd40ea0180a ("ipv4: Don't do expensive useless work
during inetdev destroy.") when deleting an interface,
fib_del_ifaddr() can be executed without any primary address
present on the dead interface.

The above is safe, but triggers some "bug: prim == NULL" warnings.

This commit avoids warning if the in_dev is dead

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
(cherry picked from commit 2c5ac2bfe56da842b7c84e99e9811f118b6f7a17)
Signed-off-by: Dhaval Giani <dhaval.giani@oracle.com>