mfd: arizona: Update registers for WM5110 DSP

DSPx_CONTROL_1 and DSPx_CLOCKING_1 are not volatile registers and are
incorrectly marked as such, fix this. Also add the DSP scratch
registers, which are frequently used to output debug info from the DSP
core.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>