ath5k: use DECLARE_EWMA

This reduces code size slightly (at least on x86/64) while also
removing memory consumption by two unsigned long values for each
ath5k device.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc drivers/net/wireless/ath/ath5k/Kconfig
Simple merge

diff --cc drivers/net/wireless/ath/ath5k/ani.c
Simple merge

diff --cc drivers/net/wireless/ath/ath5k/ath5k.h
Simple merge

diff --cc drivers/net/wireless/ath/ath5k/base.c
Simple merge

diff --cc drivers/net/wireless/ath/ath5k/debug.c
Simple merge