net: make net_random_ethaddr() more random

net: make net_random_ethaddr() more random

The net_random_ethaddr() tries to get some entropy from different
startup times of a board. The seed is initialized with get_timer() which
has only a granularity of milliseconds. We can do better if we use
get_ticks() which returns the raw timer ticks. Using this we have a
higher chance of getting different values at startup.

Signed-off-by: Michael Walle <[email protected]>
Reviewed-by: Bin Meng <[email protected]>
Acked-by: Joe Hershberger <[email protected]>