Try fallback drivers if global init for preferred drivers fails

Driver global init was considered a hard failure. Thus if, for example,
you used the Broadcom STA driver and didn't have nl80211 or cfg80211
loaded into the kernel, and specified a driver value of "nl80211,wext",
the nl80211 driver's global init would fail with the following message:

nl80211: 'nl80211' generic netlink not found
Failed to initialize driver 'nl80211'

but since global init was a hard failure, creating the supplicant
interface would fail and the WEXT driver would not be tried.
Give other drivers a chance instead.

Signed-hostap: Dan Williams <dcbw@redhat.com>
intended-for: hostap-1

wpa_supplicant/wpa_supplicant.c

@@ -1944,8 +1944,11 @@ static int wpa_supplicant_set_driver(struct wpa_supplicant *wpa_s,
 		for (i = 0; wpa_drivers[i]; i++) {
 			if (os_strlen(wpa_drivers[i]->name) == len &&
 			    os_strncmp(driver, wpa_drivers[i]->name, len) ==
-			    0)
-				return select_driver(wpa_s, i);
+			    0) {
+				/* First driver that succeeds wins */
+				if (select_driver(wpa_s, i) == 0)
+					return 0;
+			}
 		}
 
 		driver = pos + 1;