ASoC: uda134x - set reg_cache_default to uda134x_reg

After checking the code in 2.6.36,
I found this is missing during multi-component conversion.

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