mfd: arizona: Add DT options for max_channels_clocked and PDM speaker config

This patch adds DT settings for the max_channels_clocked, spk_fmt and
spk_mute pdata.

Signed-off-by: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>