wifi: brcmfmac: rename function that frees vif

wifi: brcmfmac: rename function that frees vif

Since the commit cf124db566e6 ("net: Fix inconsistent teardown and
release of private netdev state.") netdev isn't freed anymore in the
brcmf_cfg80211_free_netdev(). Adjust this function name to match what it
actually does (freeing vif).

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Link: https://patch.msgid.link/20251215103817.29598-1-zajec5@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>