board: freescale: t2080qds: Update I2C mux config

Updates the board configuration to enable use of the PCA9547 I2C mux.

Signed-off-by: Stephen Carlson <stcarlso@linux.microsoft.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/configs/T2080QDS_SECURE_BOOT_defconfig b/configs/T2080QDS_SECURE_BOOT_defconfig
index 4d33dc6..f8f031f 100644
--- a/configs/T2080QDS_SECURE_BOOT_defconfig
+++ b/configs/T2080QDS_SECURE_BOOT_defconfig
@@ -70,3 +70,4 @@
 CONFIG_RSA=y
 CONFIG_SPL_RSA=y
 CONFIG_RSA_SOFTWARE_EXP=y
+CONFIG_FSL_USE_PCA9547_MUX=y