ALSA: scarlett2: Parameterise notifications

The notification values were previously #define'd, and checked with a
series of if() statements calling functions. Replace with an array of
masks/callback function pointers, and a pointer to that array in the
scarlett2_config_set definitions.

Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Link: https://lore.kernel.org/r/0ee2a3786f9d30c89eeae59d7e933424e8f39162.1703444932.git.g@b4.vu


Signed-off-by: Takashi Iwai <tiwai@suse.de>