net: use common rand()/srand() functions

Replace rand() with the functions from lib/. The link-local network code
stores its own seed, derived from the MAC address. Thus making it
independent from calls to srand() in other modules.

Signed-off-by: Michael Walle <michael@walle.cc>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
6 files changed