re: should gpio be moved to sys/dev from sys/sys?

[matthew green <mrg%eterna.com.au@localhost>]

   Having said that, given <sys/gpio.h> is already in netbsd 5, it's too  
   late to move.
   

this hasn't prevented us from fixing other prior mistakes.

i recommend that we move it to the right place, fix the docs,
but leave a backwards compat header that generates a warning
for a couple of releases, and then remove it.


.mrg.