register_sound_dsp -- register a DSP device
(struct file_operations * fops, int dev);
File operations for the driver
Unit number to allocate
Allocate a DSP device. Unit is the number of the DSP requested.
Pass -1 to request the next free DSP unit. On success the allocated
number is returned, on failure a negative error code is returned.
This function allocates both the audio and dsp device entries together
and will always allocate them as a matching pair - eg dsp3/audio3