Documentation improvement: return code of raw1394_read_cycle_timer{,_and_clock}

"the error code of the ioctl" is always -1.  And ioctl() sets errno for us.
So let's say this in a way which is less likely to be misunderstood.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
1 file changed