Revert "Bluetooth: Voting UART clocks in non atomic context."

This reverts commit 2fed6b6f.
Bluetooth sleep mechanism is not stable with the new design.

Change-Id: I9fa7e3af5b2668764f5fb335d93a54451568f857
Signed-off-by: Ram Mohan Korukonda <rkorukon@codeaurora.org>