ASoC: bcm: add depends on HAS_DMA

add depends on HAS_DMA to Kconfig.  This fixes error reported
by kbuild test robot when building for ARCH=m32r:
ERROR: "bad_dma_ops" [sound/soc/bcm/snd-soc-cygnus.ko] undefined!

Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Mark Brown <broonie@kernel.org>