doc: board: phytec: phycore-am62x: Add USB DFU switch config

Provide boot switch config for USB DFU boot.

Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
Reviewed-by: Daniel Schultz <d.schultz@phytec.de>
diff --git a/doc/board/phytec/phycore-am62x.rst b/doc/board/phytec/phycore-am62x.rst
index bc6d524..f887065 100644
--- a/doc/board/phytec/phycore-am62x.rst
+++ b/doc/board/phytec/phycore-am62x.rst
@@ -151,6 +151,10 @@
      - 11011100
      - 00000000
 
+   * - USB DFU
+     - 11001010
+     - 00100000
+
 Further Information
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