@note Please notice that O_NONBLOCK is not supported for frontend devices, and will be silently ignored.
@note the sysname will only work if a previous call to dvb_dev_find() is issued.
@details This function is equivalent to open(2) system call: it opens a Digital TV given by the dev parameter, using the flags.
@return returns a pointer to the dvb_open_descriptor that should be used on further calls if sucess. NULL otherwise.
@brief Opens a dvb device @ingroup dvb_device
@param dvb pointer to struct dvb_device to be used @param sysname Kernel's name of the device to be opened, as obtained via dvb_dev_seek_by_adapter() or via dvb_dev_find(). @param flags Flags to be passed to open: O_RDONLY, O_RDWR and/or O_NONBLOCK