ASoC: omap-mcbsp: sidetone: Use the new callback for iclk handling

The McBSP sidetone (in OMAP3 McBSP2 and 3 module) is working with the
module's interface clock. When the sidetone is enabled the iclk must not
idle because it will result in choppy sidetone.
Switch to use the new callback for handling the iclk allow/deny idle
configuration.
For this the driver needs to get the module's ick clock and pass the clk
pointer to the callback.
In DT boot, the pdata-quirk is going to set up the callback for the driver
so save it if it is set in the pdata of the device.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>