gru: fix bug in module unload

Fix bug in module unload.  Previous code was not correctly deleting the
files in /proc.

Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>