9pfs: remove obsolete comment in v9fs_getattr()

9pfs: remove obsolete comment in v9fs_getattr()

The comment claims that we'd only support basic Tgetattr fields. This is
no longer true, so remove this comment.

Fixes: e06a765efbe3 ("hw/9pfs: Add st_gen support in getattr reply")
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <fb364d12045217a4c6ccd0dd6368103ddb80698b.1732465720.git.qemu_oss@crudebyte.com>
(cherry picked from commit 3bc4db44430f53387d17145bb52b330a830a03fe)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(Mjt: pick it to stable so the next commit applies cleanly)