ASoC: neo1973_wm8753: remove references to the neo1973-gta01 machine

The Openmoko GTA01 machine has been removed from the machine ID database,
  so we need to remove references to it as well.

Without that fix we have:
  sound/soc/samsung/neo1973_wm8753.c: In function ‘neo1973_wm8753_init’:
  sound/soc/samsung/neo1973_wm8753.c:325:2: error: implicit declaration of function ‘machine_is_neo1973_gta01’

Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@no-log.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>