Driver-Core: fix devnode callbacks for dabusb and industrialio

The build of the dabusb driver broke:

  drivers/media/video/dabusb.c:758: error: unknown field 'nodename' specified in initializer
  drivers/media/video/dabusb.c:758: warning: initialization from incompatible pointer type
  make[3]: *** wait: No child processes.  Stop.

Due to this commit:

  e454cea2: Driver-Core: extend devnode callbacks to provide permissions

Missing the dabusb driver's dabusb_nodename() callback.

Similar issues with the iio/industrialio driver in staging, pointed out
and patched by Jean Delvare.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Industrialio-parts-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>