ARM: imx: Enable btrfs support on DHSOM

The btrfs filesystem provides advanced functionality like copy-on-write
and snapshots, as well as metadata and data duplication and checksumming.
Enable btrfs in U-Boot to permit even the primary partition to be btrfs
and let system boot from it.

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
diff --git a/configs/dh_imx6_defconfig b/configs/dh_imx6_defconfig
index c7fb2c6..463c6d4 100644
--- a/configs/dh_imx6_defconfig
+++ b/configs/dh_imx6_defconfig
@@ -55,6 +55,7 @@
 CONFIG_CMD_BOOTCOUNT=y
 CONFIG_CMD_CACHE=y
 CONFIG_CMD_TIME=y
+CONFIG_CMD_BTRFS=y
 CONFIG_CMD_EXT4_WRITE=y
 CONFIG_OF_CONTROL=y
 CONFIG_OF_LIST="imx6q-dhcom-pdk2 imx6dl-dhcom-pdk2 imx6s-dhcom-drc02 imx6dl-dhcom-picoitx"