tests: ap_pmf: Stop using use_monitor=1

tests: ap_pmf: Stop using use_monitor=1

There's no need for this anymore, all the tests work without it. This
was originally used to be able to inject unprotected Deauthentication
and Disassociation frames in cases where PMF was in use, but commit
9bedf90047d6 ("nl80211: Use monitor interface for sending no-encrypt
test frames") allowed this to be done without having to for AP
operations to use the monitor interface for EAPOL frames with
use_monitor=1.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>