mfd: Avoid twl6040-codec PLL reconfiguration when not needed

Do not reconfigure the PLL in case it has been configured already
with the requested parameters.
In case of different PLL configuration do only the needed changes.
This can save considerable amount of time since we can avoid the
defined protocol (with delays) for the PLL configuration.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>