driver core: auxiliary bus: Add driver data helpers

Adds get/set driver data helpers for auxiliary devices.

Reviewed-by: Mark Gross <markgross@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Link: https://lore.kernel.org/r/20211208015015.891275-3-david.e.box@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>