[ALSA] isa libs Makefiles cleanup

This patch uses the Kconfig parameters SND_AD1848_LIB and
SND_CS4231_LIB instead of mentioning each driver that requires
the ad1848-lib or cs4231-lib separately in the Makefiles.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>