[IPV4]: Swap the ifa allocation with the"ipv4_devconf_setall" call

According to Herbert, the ipv4_devconf_setall should be called
only when the ifa is added to the device. However, failed
ifa allocation may bring things into inconsistent state.

Move the call to ipv4_devconf_setall after the ifa allocation.

Fits both net-2.6 (with offsets) and net-2.6.25 (cleanly).

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>