[ALSA] ASoC AT91xxxx build fix

This patch by Frank Madarino updates the AT91xxxx Makefile and Kconfig
to build the renamed SSC files.
Changes:-
o Rename various i2s labels to ssc

Signed-off-by: Frank Mandarino <fmandarino@endrelia.com>
Signed-off-by: Liam Girdwood <lg@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>