drm/i2c: tda998x: implement different I2S flavours

Add support for the left and right justified I2S formats as well as the
more tranditional "Philips" I2S format.

Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: Sven Van Asbroeck <TheSven73@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>