crimson/net: do not reset need_addr before learning it

crimson/net: do not reset need_addr before learning it

because we don't bind both v1 and v2 addresses, when monitor returns a
v1 peer address, as the client side, crimson-osd just drops the
connection. but this failed attempt to learn the myaddr resets
`need_addr`. and this prevents crimson-osd from learning the v2 address
returned by monitor.

in this change, we reset need_addr only after it is learned from the
peer.

Signed-off-by: Kefu Chai <kchai@redhat.com>