HID: API - fix leftovers of hidinput API in USB HID

hidinput_{open,close}() functions do not belong to usbhid, but
to the generic HID layer. Move them, and fix hooks in struct
hid_device, so that now the callbacks are done to transport-specific
_open() functions, but not input_open() functions.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>