ASoC: omap-mcbsp: Move out the FIFO check from set_threshold and get_delay

Check if the McBSP have FIFO in the omap_mcbsp_set_threshold() and
omap_mcbsp_dai_delay() delay function to skip calling the lower layer if
it is not needed.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Jarkko Nikula <jarkko.nikula@bitmer.com>
Tested-by: Jarkko Nikula <jarkko.nikula@bitmer.com>
Signed-off-by: Mark Brown <broonie@kernel.org>