net: more timeouts that reach -1

with while (timeout-- > 0); timeout reaches -1 after the loop, so the tests
below are off by one. also don't do an '< 0' test on an unsigned.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>