checkpatch: add pF/pf deprecation warning

We deprecated '%pF/%pf' printk specifiers, since '%pS/%ps' is now smart
enough to handle function pointer dereference on platforms where such
dereference is required.

Link: http://lkml.kernel.org/r/20171109234830.5067-7-sergey.senozhatsky@gmail.com
To: Tony Luck <tony.luck@intel.com>
To: Fenghua Yu <fenghua.yu@intel.com>
To: Helge Deller <deller@gmx.de>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Paul Mackerras <paulus@samba.org>
To: Michael Ellerman <mpe@ellerman.id.au>
To: James Bottomley <jejb@parisc-linux.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-ia64@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>