ASoC: sta32x: set ->component pointer in private struct

The ESD watchdog code in sta32x_watchdog() dereferences the pointer
which is never assigned.

This is a regression from a1be4cea ("ASoC: sta32x: Convert to direct
regmap API usage.") which went unnoticed since nobody seems to use that ESD
workaround.

Fixes: a1be4cea

 ("ASoC: sta32x: Convert to direct regmap API usage.")
Signed-off-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org