wifi: mac80211: make sta airtime deficit field s32 instead of s64

32 bit is more than enough range for the airtime deficit

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://lore.kernel.org/r/20220625212411.36675-2-nbd@nbd.name


Signed-off-by: Johannes Berg <johannes.berg@intel.com>