Add a new configuration option ft_r0_key_lifetime that deprecates
r0_key_lifetime. Though, the old configuration is still accepted for
backwards compatibility.
This simplifies testing. All other items are in seconds as well. In
addition, this makes dot11FTR0KeyLifetime comment match with what got
standardized in the end in IEEE Std 802.11r-2008.
Signed-off-by: Michael Braun <michael-dev@fami-braun.de>