Complete the setup for a character device's state structure
#include <qvm/cdev.h>
int cdev_setup(struct cdev_state *cds, struct vdev_s *vdev, unsigned size)
This function allocates both the internal input and output buffers, and makes them both the size given in size. If you specify a non-zero size, you must use cdev_input_*() and cdev_output_*() to read and write device data. If you don't want to use the internal buffers and use only your own input and output buffers, set size to 0 (zero). In this case, you must use cdev_read() and cdev_write() instead.
EOK on success; otherwise, an errno value.