login: support more than just power-gpio-key

login: support more than just power-gpio-key

Adding additional keys prevents this gpio-keys powerswitch from working,
e.g. this wouldn't poweroff:

button@23 {
    label = "power-switch";
    linux,code = <116>;
    gpios = <&gpio 23 1>;
};
button@25 {
    label = "KEY_A";
    linux,code = <30>;
    gpios = <&gpio 25 1>;
};

Changing ATTRS{keys}=="116" to ATTRS{keys}=="*116*" makes the
power-switch and the A key both work properly.

(David: rephrase and merge-commits)