Removed the usb_state_changed() function that was called by usb_init() without meaning.

Removed the usb_state_changed() function that was called by usb_init() without meaning.

The following call stack ensures that usb_state_changed() is called after usb_init.
///////////////////////////////////////////////////////////////////////////////////////////////////////////
extcon_init() --> usb_init() -->
event_handler_state_changed (DEVICE_NOTIFIER_STATE_START) --> add_extcon_event_handler() -->
get_extcon_init_state() -> config_parse() -> extcon_load_uevent() -> extcon_update() -> usb_state_changed()
///////////////////////////////////////////////////////////////////////////////////////////////////////////

Also, when usb_state_changed() is called from usb_init,
the extcon value is always -1 because the extcon initial value has not yet been retrieved.

The initial state of usb_state_changed() is -1, and usb_state_changed(-1) does nothing.

Change-Id: I77d774c9a396b3773203a69db83aa408e315205a