int dvb_ca_en50221_read_data (struct dvb_ca_private * ca, int slot, u8 * ebuf, int ecount);
data from the CAM. The data can either be stored in a supplied buffer, or automatically be added to the slot's rx_buffer.
param ca CA instance. param slot Slot to read from. param ebuf If non-NULL, the data will be written to this buffer. If NULL, the data will be added into the buffering system as a normal fragment. param ecount Size of ebuf. Ignored if ebuf is NULL.
return Number of bytes read, or < 0 on error