wpa_supplicant: fix for no wifi in network manager

Without this patch I can't get wifi working with M3 device, kernel 2.6.34.14 (latest commit of develop branch at https://github.com/J1nx-Hackable-Gadgets/buildroot-linux-kernel-m3/tree/1b48458d3e670a7d2f2cd968e9ae7387887469a8 ).
I was only getting "ADDRCONF(NETDEV_UP): wlan0: link is not ready" in dmesg.

This comes commit
"Revert wifi back to WEXT as default" at https://github.com/J1nx-Hackable-Gadgets/buildroot-M3-MX/commit/0886d81159bcf08392e536801f7bc806f79eadb4