ASoC: omap-abe-twl6040: Correct dmic-codec device registration

The dmic-codec was registered within the platform_driver's probe function,
which can cause deferred probe to run in loops as reported and analyzed by
Russell King.

Use module_init/exit in the driver and handle the dmic-codec device
registration and removal at that level instead of the platform_driver
probe/remove.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reported-by: Russell King <rmk+kernel@armlinux.org.uk>
Tested-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Mark Brown <broonie@kernel.org>