[POWERPC] macintosh: Use common modalias generation for macio_sysfs

There is now a common function to generate the modalias string,
so use it. We just need to add the \n at the end.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>