[LinuxPPS] refclock_nmea patch

[Udo van den Heuvel]

I see in the LinuxPPS source that a port is checked: First we check if
current device is a PPS valid PPS one.
What is the use? (if this test fails on my /dev/gps0?)
So what use is it then to make /dev/gps0 if we have an automagic /dev/pps0?

(just trying to understand)