[ALSA] Add SPI devices to ALSA Kconfig and Makefile

This patch adds SPI devices in the ALSA diretory, including the Kconfig and
Makefile.

Signed-off-by: Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>