ASoC: atmel: sam9x5_wm8731: remove platform_set_drvdata

When call snd_soc_register_card, it will set driver data to this
device through dev_set_drvdata, then in driver, no need to call
platform_set_drvdata again, so remove it.

Signed-off-by: Bo Shen <voice.shen@atmel.com>
ASoC: atmel: sam9x5_wm8731: fix oops when unload module

As the priv is not assigned to card->drvdata, it is NULL, so when
unload module, it will cause NULL pointer oops.
Assign priv to card->drvdata to fix this issue.

Signed-off-by: Bo Shen <voice.shen@atmel.com>
ASoC: sam9x5_wm8731: change to work in DSP A mode

Change sam9x5 with wm8731 work in DSP A mode, this will fix the
left/right channel swap issue.

Signed-off-by: Bo Shen <voice.shen@atmel.com>
Tested-by: Richard Genoud <richard.genoud@gmail.com>
ASoC: atmel_ssc_dai: add dai trigger ops

According to the SSC specifiation, it should be enabled after DMA is
enabled. So, add trigger operation to make sure the right sequence.

Signed-off-by: Bo Shen <voice.shen@atmel.com>
Tested-by: Richard Genoud <richard.genoud@gmail.com>
ASoC: wm8731: fix dsp mode configuration

According to WM8731 "PD, Rev 4.9 October 2012" datasheet, when it
works in DSP mode A, LRP = 1, while works in DSP mode B, LRP = 0.
So, fix LRP for DSP mode as the datesheet specification.

Signed-off-by: Bo Shen <voice.shen@atmel.com>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>