ALSA: ASoC: Remove references to Endrelia ETI-B1 board

The ASoC machine drivers for this board were only provided as examples
for the new AT91 ASoC platform driver.  Since the ETI-B1 board is
proprietary and there are other AT91 ASoC machine drivers available,
it makes sense to remove these drivers.

Signed-off-by: Frank Mandarino <fmandarino@endrelia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>