RME RayDAT and AIO cards are new designs with different register
settings. Since we need to distinguish them from older cards multiple
times in the driver, refactor the code into a separate helper function.

No functional change intended.
Signed-off-by: Adrian Knoth <adi@drcomp.erfurt.thur.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>