V4L/DVB: Saa7134: rename dmasound_{init,exit}

Two different exports with the same name are not a good idea:

$ grep -r EXPORT_SYMBOL\(dmasound_init\) *
drivers/media/video/saa7134/saa7134-core.c:EXPORT_SYMBOL(dmasound_init);
sound/oss/dmasound/dmasound_core.c:EXPORT_SYMBOL(dmasound_init);
$

This patch renames the saa7134 dmasound_{init,exit} to
saa7134_dmasound_{init,exit}.

Signed-off-by: Adrian Bunk <bunk@stusta.de>