arm: fsl: imx8mn_bsh_smm_s2: Migrate to OF_UPSTREAM

Migrate imx8mn_bsh_smm_s2 and imx8mn_bsh_smm_s2pro boards to OF_UPSTREAM.

Signed-off-by: Patrick Barsanti <patrick.barsanti@amarulasolutions.com>
Tested-by: Michael Trimarchi <michael@amarulasolutions.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
diff --git a/configs/imx8mn_bsh_smm_s2_defconfig b/configs/imx8mn_bsh_smm_s2_defconfig
index 0e0a548..b4351a3 100644
--- a/configs/imx8mn_bsh_smm_s2_defconfig
+++ b/configs/imx8mn_bsh_smm_s2_defconfig
@@ -8,7 +8,7 @@
 CONFIG_NR_DRAM_BANKS=1
 CONFIG_ENV_SIZE=0x2000
 CONFIG_DM_GPIO=y
-CONFIG_DEFAULT_DEVICE_TREE="imx8mn-bsh-smm-s2"
+CONFIG_DEFAULT_DEVICE_TREE="freescale/imx8mn-bsh-smm-s2"
 CONFIG_SPL_TEXT_BASE=0x912000
 CONFIG_TARGET_IMX8MN_BSH_SMM_S2=y
 CONFIG_OF_LIBFDT_OVERLAY=y