container_of: remove container_of_safe()

container_of: remove container_of_safe()

It came in from a staging driver that has been long removed from the
tree, and there are no in-kernel users of the macro, and it's very
dubious if anyone should ever use this thing, so just remove it
entirely.

Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20221024123933.3331116-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>