driver core: attribute_container: Remove unused functions

I can't find any use of 'attribute_container_add_class_device_adapter'
or 'attribute_container_trigger' in git history.
Their export decls went in 2006:
  commit 1740757e ("[PATCH] Driver Core: remove unused exports")

and their docs disappeared in 2016:
  commit 47cb398d ("Docs: sphinxify device-drivers.tmpl")

Remove them.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Link: https://lore.kernel.org/r/20240913010955.1393995-1-linux@treblig.org


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