wifi: iwlwifi: mvm: Remove unused iwl_mvm_rx_missed_vap_notif

iwl_mvm_rx_missed_vap_notif() was added in 2019 by
commit 449a29d0 ("iwlwifi: mvm: add notification for missed VAP")

but hasn't been used.

Remove it.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://patch.msgid.link/20241223013202.340180-3-linux@treblig.org