ata: pata_ns87415.c: Document support on parisc with superio chip

I tested this driver on my HP PA-RISC C3000 workstation and it does
work with the built-in TEAC CD-532E-B CD-ROM drive.
So drop the TODO item and adjust the file header.

Signed-off-by: Helge Deller <deller@gmx.de>