We should protect hw_pll handler with power save wrappers and
also modularize hw_pll handler properly for better readability.

Also add a debug message to track chip resets on pll hang condition.
Signed-off-by: NSenthil Balasubramanian <senthilkumar@atheros.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>