android/hid: Add handling of HAL_EV_HID_CONN_STATE

android/hid: Add handling of HAL_EV_HID_CONN_STATE

This patches generate proper events when the connection state changes:

>hidhost connect
BlueZ D: android/hal-hidhost.c:hh_connect()
connection_state_cb: bd_addr= connection_state=BTHH_CONN_STATE_CONNECTING
if_hh->connect: BT_STATUS_SUCCESS
connection_state_cb: bd_addr= connection_state=BTHH_CONN_STATE_CONNECTED
>hidhost disconnect
BlueZ D: android/hal-hidhost.c:hh_disconnect()
connection_state_cb: bd_addr= connection_state=BTHH_CONN_STATE_DISCONNECTING
if_hh->disconnect: BT_STATUS_SUCCESS
connection_state_cb: bd_addr= connection_state=BTHH_CONN_STATE_DISCONNECTED