mac80211: minstrel: make prob_ewma u16 instead of u32

Saves about 1.2 KiB memory per station

Signed-off-by: Felix Fietkau <[e-mail]>
Signed-off-by: Johannes Berg <[e-mail]>

net/mac80211/rc80211_minstrel.h

···
 	/* statistis of packet delivery probability
 	 *  prob_ewma - exponential weighted moving average of prob
 	 *  prob_ewmsd - exp. weighted moving standard deviation of prob */
-	unsigned int prob_ewma;
+	u16 prob_ewma;
 	u16 prob_ewmv;
 
 	/* maximum retry counts */