bluesleep: implement to support bluedroid

"#define BT_BLUEDROID_SUPPORT 1" -> support BlueDroid
"#define BT_BLUEDROID_SUPPORT 0" -> support BlueZ

Since BlueDroid does not use kernel space HCI driver now, we add the
below 2 /proc nodes to make BlueDroid able to send HCI events to
bluesleep driver.

write 1 to /proc/bluetooth/sleep/lpm -> equivalent to HCI_DEV_REG event
write 0 to /proc/bluetooth/sleep/lpm -> equivalent to HCI_DEV_UNREG event
write 1 to /proc/bluetooth/sleep/btwrite -> equivalent to HCI_DEV_WRITE event