netlink: fix interface dump.

The current code missed interface addition when reallocating
temporary buffer.
Tweak the code to perform the reallocation first and add
interface afterwards unconditionally.

Reported by: Marek Zarychta <zarychtam@plan-b.pwste.edu.pl>
Approved by: re (cperciva)

(cherry picked from commit 86fd0bdba540132ae298457e160b651f61d1db6b)
(cherry picked from commit a800622765b1e7cab79fa857e9a671e6c0c1ccec)