wifi: iwlwifi: mvm: Remove unused iwl_mvm_ftm_add_pasn_sta

iwl_mvm_ftm_add_pasn_sta() was added in 2020 by
commit 0739a7d7 ("iwlwifi: mvm: initiator: add option for adding a
PASN responder")
but hasn't been used.

Remove it.

That was the only caller of iwl_mvm_ftm_remove_pasn_sta().

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/20241223013202.340180-5-linux@treblig.org