rc: Chase bfb202c455 and remove ifconfig down/up for wpa_supplicant

bfb202c455 addresses the CTRL-EVENT-SCAN-FAILED. Upstream d807e289d
caused FreeBSD regression in driver_bsd.c, which this rc.d patch
worked around. As of bfb202c455 this workaround is no longer needed.

Reviewed by:	bz (for wireless)
MFC after:	10 days
X-MFC with:	bfb202c455
Differential Revision:	https://reviews.freebsd.org/D39257

libexec/rc/rc.d/wpa_supplicant

@@ -12,7 +12,6 @@
 
 name="wpa_supplicant"
 desc="WPA/802.11i Supplicant for wireless network devices"
-start_postcmd="wpa_poststart"
 rcvar=
 
 ifn="$2"
@@ -20,11 +19,6 @@ if [ -z "$ifn" ]; then
 	return 1
 fi
 
-wpa_poststart() {
-	ifconfig ${ifn} down
-	ifconfig ${ifn} up
-}
-
 if is_wired_interface ${ifn} ; then
 	driver="wired"
 else