armv8: ls1046a: Enable spl_board_init() function

CONFIG_SPL_BOARD_INIT is used for SPL boot. It is only enabled for
secure boot at this moment. Enable it in defconfig files for SPL
build.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/configs/ls1046aqds_nand_defconfig b/configs/ls1046aqds_nand_defconfig
index cdcc25d..a3c6065 100644
--- a/configs/ls1046aqds_nand_defconfig
+++ b/configs/ls1046aqds_nand_defconfig
@@ -8,6 +8,7 @@
 CONFIG_NAND_BOOT=y
 CONFIG_BOOTDELAY=10
 CONFIG_SPL=y
+CONFIG_SPL_BOARD_INIT=y
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_USE_SECTOR=y
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR=0x110
 CONFIG_HUSH_PARSER=y