wpa_supplicant: Try all drivers by default

wpa_supplicant: Try all drivers by default

Some distros carry patches to specify driver fallback, but only in
specific conditions (e.g. the systemd service definition[1]). This leaves
other wpa_supplicant instances needing to define fallback themselves,
which leads to places where wpa_supplicant thinks it can't find a
driver[2]. Instead, when -D is not specified, have wpa_supplicant try
all the drivers it was built with in an attempt to find a working one
instead of just giving up if the first doesn't work.

[1] https://salsa.debian.org/debian/wpa/-/blob/debian/unstable/debian/patches/networkd-driver-fallback.patch
[2] https://bugs.launchpad.net/netplan/+bug/1814012

Signed-off-by: Kees Cook <kees@ubuntu.com>