feat(plat/nxp/lx2): add SUPPORTED_BOOT_MODE definition

Add macro of SUPPORTED_BOOT_MODE for board lx2160ardb, lx2160aqds,
lx2162aqds.

Signed-off-by: Biwen Li <biwen.li@nxp.com>
Signed-off-by: Jiafei Pan <Jiafei.Pan@nxp.com>
Change-Id: I4451ca030eca79c9bc5fee928eec497a7f0e878c
diff --git a/plat/nxp/soc-lx2160a/lx2160ardb/platform.mk b/plat/nxp/soc-lx2160a/lx2160ardb/platform.mk
index 5f76813..ffb5fad 100644
--- a/plat/nxp/soc-lx2160a/lx2160ardb/platform.mk
+++ b/plat/nxp/soc-lx2160a/lx2160ardb/platform.mk
@@ -40,6 +40,10 @@
 BL2_SOURCES	+=	${BOARD_PATH}/ddr_init.c\
 			${BOARD_PATH}/platform.c
 
+SUPPORTED_BOOT_MODE	:=	flexspi_nor	\
+				sd		\
+				emmc
+
 # Adding platform board build info
 include plat/nxp/common/plat_make_helper/plat_common_def.mk