dtc(1): Update to upstream 006664a

Highlights:

• Passing "-" to -o will now cause output to go to stdout
• Path-based syntactic sugar for overlays is now accepted. This looks like:

/dts-v1/;
/plugin/;

&{/soc} {

sid: eeprom@1c14000 {
    compatible = "allwinner,sun8i-h3-sid";
    reg = <0x1c14000 0x400>;
    status = "okay";
};

};

MFC after: 3 days