configs: update TFABOOT defconfigs for SD boot support

update TFABOOT defconfig for SD boot on below NXP chasis2
and chasis3 platforms:

ls1043a, ls1046a, ls1088a and ls2088a.

Signed-off-by: Rajesh Bhagat <rajesh.bhagat@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>
diff --git a/configs/ls2088ardb_tfa_defconfig b/configs/ls2088ardb_tfa_defconfig
index bb5e4f8..016d8bc 100644
--- a/configs/ls2088ardb_tfa_defconfig
+++ b/configs/ls2088ardb_tfa_defconfig
@@ -33,6 +33,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="fsl-ls2088a-rdb-qspi"
 CONFIG_ENV_IS_IN_FLASH=y
 CONFIG_ENV_IS_IN_SPI_FLASH=y
+CONFIG_ENV_IS_IN_MMC=y
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_DM=y
 CONFIG_FSL_CAAM=y