ASoC: Add missing dev_set_drvdata in mpc8610_hpcd_probe

Otherwise, calling dev_get_drvdata in mpc8610_hpcd_remove returns NULL.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Timur Tabi <timur@freescale.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>