ath10k: fix naming Peer stats rssi_changed field in 10.2.4

Fix naming of peer stats rssi_changed field in 10.2.4 to make it
more readable. As of now this field is not used, but necessary to
pull in fw_stats with appropriate length.

Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>