V4L/DVB (13412): SMS_SIANO_MDTV should depend on HAS_DMA

When building for Sun 3:

drivers/built-in.o: In function `smscore_unregister_device':
drivers/media/dvb/siano/smscoreapi.c:723: undefined reference to `dma_free_coherent'
drivers/built-in.o: In function `smscore_register_device':
drivers/media/dvb/siano/smscoreapi.c:365: undefined reference to `dma_alloc_coherent'

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>