kconfig: ls1021a: add SUPPORT_SPL

Add SUPPORT_SPL feature for SD and NAND boot on
LS1021AQDS and LS1021ATWR.

Signed-off-by: Alison Wang <alison.wang@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 7a64b66..11ae5f8 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -730,10 +730,12 @@
 config TARGET_LS1021AQDS
 	bool "Support ls1021aqds_nor"
 	select CPU_V7
+	select SUPPORT_SPL
 
 config TARGET_LS1021ATWR
 	bool "Support ls1021atwr_nor"
 	select CPU_V7
+	select SUPPORT_SPL
 
 config TARGET_BALLOON3
 	bool "Support balloon3"