ASoC: sgtl5000: Fix driver probe after reset

ASoC: sgtl5000: Fix driver probe after reset

After a 'reboot' command in Linux or after pressing the system's reset button
the sgtl5000 driver fails to probe:

sgtl5000 0-000a: Device with ID register ffff is not a sgtl5000
sgtl5000 0-000a: ASoC: failed to probe CODEC -19
imx-sgtl5000 sound.12: ASoC: failed to instantiate card -19
imx-sgtl5000 sound.12: snd_soc_register_card failed (-19)

sgtl5000 codec does not have a reset line, nor a reset command in software, so
after a system reset the codec does not contain the default register values
from sgtl5000_reg_defaults[] anymore, as these are only valid after a
power-on-reset cycle.

Fix this issue by explicitly reading all the reset register values from
sgtl5000_reg_defaults[] and writing them back into sgtl5000 to ensure a sane
state.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Tested-by: Eric Nelson <eric.nelson@boundarydevices.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>