[PATCH] fuse: fix fuse_dev_poll() return value

fuse_dev_poll() returned an error value instead of a poll mask.  Luckily (or
unluckily) -ENODEV does contain the POLLERR bit.

There's also a race if filesystem is unmounted between fuse_get_conn() and
spin_lock(), in which case this event will be missed by poll().

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>