ALSA: hdspm - Add support for RME RayDAT and AIO

Incorporate changes by Florian Faber into hdspm.c. Code taken from

   http://wiki.linuxproaudio.org/index.php/Driver:hdspe

Heavily reworked to mostly comply with the coding standard (whitespace
fixes, line width, C++ style comments)

The code was tested and confirmed to be working on RME RayDAT.
Signed-off-by: Adrian Knoth <adi@drcomp.erfurt.thur.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>