udoo_neo: Select DM_SERIAL and drop iomux board level init

Convert to DM_SERIAL and drop the iomux board file
level init as it's handled as part of the DM serial
layer instead.

Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
Reviewed-by: Fabio Estevam <festevam@denx.de>
diff --git a/configs/udoo_neo_defconfig b/configs/udoo_neo_defconfig
index a450482..73ab0f0 100644
--- a/configs/udoo_neo_defconfig
+++ b/configs/udoo_neo_defconfig
@@ -22,7 +22,6 @@
 CONFIG_DISTRO_DEFAULTS=y
 CONFIG_SYS_MONITOR_LEN=409600
 CONFIG_BOOTCOMMAND="run findfdt; run distro_bootcmd"
-CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SYS_SPL_MALLOC=y
 CONFIG_SPL_ENV_SUPPORT=y
 CONFIG_SPL_FS_EXT4=y
@@ -60,6 +59,7 @@
 CONFIG_DM_REGULATOR_FIXED=y
 CONFIG_DM_REGULATOR_ANATOP=y
 CONFIG_DM_REGULATOR_PFUZE100=y
+CONFIG_DM_SERIAL=y
 CONFIG_MXC_UART=y
 CONFIG_IMX_THERMAL=y
 CONFIG_USB=y