Split out the PHY error counter update from ath9k_hw_ani_monitor_*, reuse
it in ath9k_hw_proc_mib_event (merged from ath9k_hw_proc_mib_event_old
and ath9k_hw_proc_mib_event_new).
Signed-off-by: Felix Fietkau <nbd@openwrt.org> Signed-off-by: John W. Linville <linville@tuxdriver.com>