[PARISC] Mention PA-RISC in NS87415 help

Mention PA-RISC in NS87415 help. PA-RISC [BCJ]xxx0 workstations come with
NS87415 integrated for their CD-ROM drives.

Signed-off-by: Matthew Wilcox <willy@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>