uhid: Fix uhidev attach bug and remove hidev_tag_t typedef
uhid: Move generic HID code to sys/dev/hidThis change introduces a bus agnostic HID interface (sys/dev/hid/hidev.h)and splits the uhid driver into a shareable (sys/dev/hid/uhid_common.c) andUSB specific (sys/dev/usb/uhid.c) code.