board: freescale: ls1046a: 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/ls1046aqds_tfa_defconfig b/configs/ls1046aqds_tfa_defconfig
index f64d0d6..aebd9e6 100644
--- a/configs/ls1046aqds_tfa_defconfig
+++ b/configs/ls1046aqds_tfa_defconfig
@@ -82,3 +82,4 @@
 CONFIG_USB_XHCI_HCD=y
 CONFIG_USB_XHCI_DWC3=y
 CONFIG_EFI_LOADER_BOUNCE_BUFFER=y
+CONFIG_FSL_USE_PCA9547_MUX=y