i2o proc reading oops

Fix oops on reading from some i2o proc files (i2o_seq_show_driver_store() and
other) because their handlers uses "exec" field in struct i2o_controller

Signed-off-by: Vasily Averin <vvs@sw.ru>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Markus Lidel <Markus.Lidel@shadowconnect.com>
Acked-by: Kirill Korotaev <dev@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>