[ALSA] cmipci: allow 96 kHz playback on non-multichannel rear

Move the code that enables 96 kHz out of the if() that checks for
availability of both DMA channels so that it is enabled even when
another stream is playing on the front channels.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>