procfs: Kill the bkl in ioctl

There are no more users of procfs that implement the ioctl
callback. Drop the bkl from this path and warn on any use
of this callback.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: John Kacur <jkacur@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>