Bluetooth: btmrvl: wait for HOST_SLEEP_ENABLE event in suspend

After BT_CMD_HOST_SLEEP_ENABLE command finishes, driver should
wait until getting BT_EVENT_HOST_SLEEP_ENABLE event to complete
suspend procedure.
Without this patch the suspend handler would return success
earlier. By the time when the BT_EVENT_HOST_SLEEP_ENABLE event
comes in the controller driver could have already turned off the
bus clock. This causes kernel crash or system reboot eventually.

Cc: <stable@vger.kernel.org> # 3.13+
Signed-off-by: Chin-Ran Lo <crlo@marvell.com>
Signed-off-by: Jeff CF Chen <jeffc@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>