namei.c: remove utterly outdated comment

We don't have a routine called namei() anymore since at least 2.3.x, and
the comment is just totally out of sync with the current lookup logic.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>