container_of: Update header inclusions

The commit 848dba78 ("container_of: remove container_of_safe()")
removed the code that uses err.h. Replace the inclusion by stddef.h
which provides offsetof() definition which is still in use.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230130111746.59830-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>