imx: imx8mm: imx8mm-kontron-n801x-s: convert options to Kconfig

CONFIG_SPL_MMC and CONFIG_SPL_SERIAL

Signed-off-by: Heiko Thiery <heiko.thiery@gmail.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
diff --git a/configs/kontron-sl-mx8mm_defconfig b/configs/kontron-sl-mx8mm_defconfig
index 35d12fc..940bf07 100644
--- a/configs/kontron-sl-mx8mm_defconfig
+++ b/configs/kontron-sl-mx8mm_defconfig
@@ -15,6 +15,8 @@
 CONFIG_DEFAULT_DEVICE_TREE="imx8mm-kontron-n801x-s"
 CONFIG_SPL_TEXT_BASE=0x7E1000
 CONFIG_TARGET_KONTRON_MX8MM=y
+CONFIG_SPL_MMC=y
+CONFIG_SPL_SERIAL=y
 CONFIG_BOOTCOUNT_BOOTLIMIT=3
 CONFIG_SPL=y
 CONFIG_DISTRO_DEFAULTS=y