hostapd: add default value to eapol_version (#20641)

hostapd: add default value to eapol_version (#20641)

r46861 introduced a new option eapol_version to hostapd, but did not
provide a default value. When the option value is evaluated,
the non-existing value causes errors to the systen log:
"netifd: radio0: sh: out of range"

Add a no-op default value 0 for eapol_version. Only values 1 or 2 are
actually passed on, so 0 will not change the default action in hostapd.

Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@47361 3c298f89-4303-0410-b956-a3cf2f4a3e73