ASoC: arizona: Add data structure for voice trigger notifier

64-bit builds would generate a warning when we passed the core number as
a pointer through the notifier data:

sound/soc/codecs/cs47l24.c:1091:13: warning: cast to pointer from
integer of different size [-Wint-to-pointer-cast]
             (void *)i);

Rather than just fix this up with more casting add a data structure that
holds information for the notifier chain. This will make it easier to
add additional information in the future as well.

Fixes: 7baa7e24 ("ASoC: arizona: Add event notification on voice trigger events")
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>