ASoC: Fix build error in sound/soc/kirkwood/kirkwood-i2s.c

ASoC: Fix build error in sound/soc/kirkwood/kirkwood-i2s.c

Since commit db33f4de "ARM: Orion: Remove address map info from all platform data structures",
the dram is removed from struct kirkwood_asoc_platform_data.

This patch fixes below build error:
  CC      sound/soc/kirkwood/kirkwood-i2s.o
sound/soc/kirkwood/kirkwood-i2s.c: In function 'kirkwood_i2s_dev_probe':
sound/soc/kirkwood/kirkwood-i2s.c:444: error: 'struct kirkwood_asoc_platform_data' has no member named 'dram'
sound/soc/kirkwood/kirkwood-i2s.c:450: error: 'struct kirkwood_asoc_platform_data' has no member named 'dram'
make[3]: *** [sound/soc/kirkwood/kirkwood-i2s.o] Error 1
make[2]: *** [sound/soc/kirkwood] Error 2
make[1]: *** [sound/soc] Error 2
make: *** [sound] Error 2

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>