bluetooth: Vote clock off on protocol close

UART clock is voted off after an idle timeout of one second. But if
Bluetooth is turned off before idle timeout expires, UART clock remains
on. This prevents host from going into power collapse and results in
higher current. Explicitly vote UART clocks off in during Bluetooth
turn off.

Change-Id: I0847dacc94ac24a9ccce177943272a32722ef61d
Signed-off-by: Kamal Negi <kamaln@codeaurora.org>