Fix issue where bluesleep idle timer is not started

Sometimes allow_device_sleep() is called before wake_assert, this result in transmit_done
does not start idle timer. This is because the "wake_state" does not match while
allow_device_sleep() is called before wake_assert() is called. So start idle timer
anyway when transmit_done is called.

Bug: 23754156
Change-Id: I5437aea0abc4b7f5cf847701e2d0a889c6823fcb