ASoC: atmel: don't use devm_pinctrl_get_select_default() in probe

Since commit ab78029 (drivers/pinctrl: grab default handles from device core),
we can rely on device core for setting the default pins.

Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Linus Walleij <linus.walleij@linaro.org> (personally at LCE13)
Acked-by: Bo Shen <voice.shen@atmel.com>
Signed-off-by: Mark Brown <broonie@linaro.org>