ASoC: arizona: Correct types of mixer texts and values

The core expects "const char * const" and "unsigned int" for enum
controls, various places in Arizona use "const char *" and "int".
This patch corrects the type of these arrays.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>