Port USB Fastcharge : originally ported by showp1984

         https://github.com/showp1984/bricked-pyramid-3.0/commit/9074f71ce46a984ad790e1b6ffb2ff4221d7afd1
         https://github.com/showp1984/bricked-pyramid-3.0/commit/515dedcf5fa3268942b282f0ecbb36533d4245da

        USB forced fast charge v2

        Use sysfs interface to change behaviour :

         * /sys/kernel/fast_charge/force_fast_charge (rw)
         *
         *   0 - disabled (default)
         *   1 - substitute AC to USB charging always
         *   2 - substitute AC to USB charging only if no USB peripheral is detected

        For informational purposes I've also added a read-only sysfs file that indicates the current USB state :

         * /sys/kernel/fast_charge/USB_peripheral_detected (ro)
         *
         * The state will be returned in clear text (Yes/No).

        For informational purposes I've also added a read-only sysfs file that indicates the detected USB port type :

         * /sys/kernel/fast_charge/USB_porttype_detected (ro)
         *
         * The port type will be returned in clear text.

Change-Id: Iccd151e5bcd07af74859f5fe177312a12fb891c7