mwifiex: remove misleading disconnect message

Disconnect message in mwifiex_reset_connect_state() would displays
necessary information. We unnecessarily have exactly same message in
cfg80211_disconnect(). As priv->cfg_bssid is cleared at this point of
time, it prints incorrect(all zero) MAC.

This message is removed here.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>