rc: Chase bfb202c4554a and remove ifconfig down/up for wpa_supplicant

bfb202c4554a addresses the CTRL-EVENT-SCAN-FAILED. Upstream d807e289d
caused FreeBSD regression in driver_bsd.c, which this rc.d patch
worked around. As of bfb202c4554a this workaround is no longer needed.

Reviewed by: bz (for wireless)
MFC after: 10 days
X-MFC with: bfb202c4554a
Differential Revision: https://reviews.freebsd.org/D39257