board: colibri-imx8x: add 2nd ethernet address

All Colibri iMX8X variants have 2nd RGMII on SoC, so add the address
for 2nd ethernet.

Signed-off-by: Andrejs Cainikovs <andrejs.cainikovs@toradex.com>
diff --git a/board/toradex/colibri-imx8x/Kconfig b/board/toradex/colibri-imx8x/Kconfig
index b89840a..cb11e2c 100644
--- a/board/toradex/colibri-imx8x/Kconfig
+++ b/board/toradex/colibri-imx8x/Kconfig
@@ -12,6 +12,9 @@
 config TDX_CFG_BLOCK
 	default y
 
+config TDX_CFG_BLOCK_2ND_ETHADDR
+	default y
+
 config TDX_HAVE_MMC
 	default y