armv8: ls1088ardb: Add distro boot support

Distro boot support gives flexibility to run distro RFS like Ubuntu
being deployed from SD card or SATA drive. If it fails to detect
external storage, fall back to qspi/sd boot.

Enable this by default in RDB's defconfig by selecting
CONFIG_DISTRO_DEFAULTS

Signed-off-by: Ashish Kumar <Ashish.Kumar@nxp.com>
Signed-off-by: Zhang Ying <zhangying@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>
diff --git a/configs/ls1088ardb_qspi_defconfig b/configs/ls1088ardb_qspi_defconfig
index 9cc875a..1f3d581 100644
--- a/configs/ls1088ardb_qspi_defconfig
+++ b/configs/ls1088ardb_qspi_defconfig
@@ -2,6 +2,7 @@
 CONFIG_TARGET_LS1088ARDB=y
 CONFIG_FSL_LS_PPA=y
 CONFIG_DEFAULT_DEVICE_TREE="fsl-ls1088a-rdb"
+CONFIG_DISTRO_DEFAULTS=y
 # CONFIG_SYS_MALLOC_F is not set
 CONFIG_FIT_VERBOSE=y
 CONFIG_OF_BOARD_SETUP=y