boards: up-bridge-the-gap: adopt new zephyr:board directive and role

This updates the documentation of all the UP boards to use
the new `zephyr:board::` directive.

Signed-off-by: Benjamin Cabé <[email protected]>

Author: kartben

boards/up-bridge-the-gap/up_squared/doc/index.rst

@@ -1,7 +1,4 @@
-.. _up_squared:
-
-UP Squared
-##########
+.. zephyr:board:: up_squared
 
 Overview
 ********
@@ -11,12 +8,6 @@ performance and low power consumption. It features the latest Intel |reg| Apollo
 Lake Celeron |trade| and Pentium |trade| Processors with only 4W of Scenario Design Power and
 a powerful and flexible Intel |reg| FPGA Altera MAX 10 onboard.
 
-.. figure:: img/up_squared.jpg
-   :align: center
-   :alt: UP Squared
-
-   Up Squared (Credit: https://up-board.org)
-
 This board configuration enables kernel support for the `UP Squared`_ board.
 
 .. note::

boards/up-bridge-the-gap/up_squared_pro_7000/doc/up_squared_pro_7000.rst

@@ -1,9 +1,4 @@
-:orphan:
-
-.. _up_squared_pro_7000_board:
-
-UP Squared Pro 7000
-###################
+.. zephyr:board:: up_squared_pro_7000
 
 Overview
 ********