doc/configuration: split DediprogFlashDriver example

Driver and image are not expected on the same indentation level. Other
drivers use an example with two sections, one for the driver and one for
global options like "images". Do the same for the DediprogFlashDriver to
prevent confusion.

Signed-off-by: Bastian Krause <bst@pengutronix.de>

Author: Bastian-Krause

doc/configuration.rst

@@ -3024,6 +3024,9 @@ The :any:`DediprogFlashDriver` is used to flash an SPI device using DediprogFlas
 
    DediprogFlashDriver:
      image: 'foo'
+
+.. code-block:: yaml
+
    images:
      foo: '../images/image_to_load.raw'