ASoC: omap-mcpdm: Drop pdmclk clock handling

This reverts commit 65aca64d.

The patches for twl6040 MFD and clk missed the merge window and
causing the McPDM driver to never probe since it is put back to
the deferred list because the missing drivers.

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