hostapd: Add wpa_psk_file option to netifd.sh

hostapd: Add wpa_psk_file option to netifd.sh

The wpa_psk_file option offers the possibility to use a different WPA-PSK key for each client. The directive points to a file with the following syntax:

mac_address wpa_passphrase_or_hex_key

Example:

00:11:22:33:44:55 passphrase_for_client_1
00:11:22:33:44:67 passphrase_for_client_2
00:11:22:33:44:89 0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef

So it is possible to specify both ASCII passphrases and raw 64-chars hex keys.

Signed-off-by: Vittorio Gambaletta <openwrt@vittgam.net>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43001 3c298f89-4303-0410-b956-a3cf2f4a3e73