xilinx: Add option to select SC id instead of DUT id for SC support

Reading MAC address from on board EEPROM requires different type for System
Controller (SC).

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/90bb7cc5463568a690b979f18c8d42556986b46d.1669204122.git.michal.simek@amd.com
diff --git a/board/xilinx/Kconfig b/board/xilinx/Kconfig
index 746a233..7b31d7e 100644
--- a/board/xilinx/Kconfig
+++ b/board/xilinx/Kconfig
@@ -82,3 +82,12 @@
 	  information present in the device. The FRU Information is used
 	  to primarily to provide "inventory" information about the boards
 	  that the FRU Information Device is located on.
+
+config FRU_SC
+	bool "FRU system controller decoding"
+	help
+	  Xilinx System Controller (SC) FRU format is describing boards from two
+	  angles. One from DUT and then from SC. DUT is default option for
+	  the main CPU. SC behaves more or less as slave and have different ID.
+	  If you build U-Boot for SC you should enable this option to get proper
+	  MAC address.