[PATCH] pipe: remove redundant fifo_poll abstraction

Remove a redundant fifo_poll() abstraction from fs/pipe.c and adds a big
fat comment stating we set POLLERR for FIFOs too on Linux unlike most
Unices.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>