x86-32: Export kernel_stack_pointer() for modules

commit cb57a2b4cff7edf2a4e32c0163200e9434807e0a upstream.

Modules, in particular oprofile (and possibly other similar tools)
need kernel_stack_pointer(), so export it using EXPORT_SYMBOL_GPL().

Cc: Yang Wei <wei.yang@windriver.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Jun Zhang <jun.zhang@intel.com>
Link: http://lkml.kernel.org/r/20120912135059.GZ8285@erda.amd.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Robert Richter <rric@kernel.org>
Cc: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
Cc: Philip Müller <philm@manjaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux 3.0.55