Convert CONFIG_SPL_BSS_START_ADDR to Kconfig

This converts the following to Kconfig:
   CONFIG_SPL_BSS_START_ADDR

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/j721s2_evm_a72_defconfig b/configs/j721s2_evm_a72_defconfig
index 0628e29..7903add 100644
--- a/configs/j721s2_evm_a72_defconfig
+++ b/configs/j721s2_evm_a72_defconfig
@@ -35,6 +35,8 @@
 CONFIG_BOOTCOMMAND="run findfdt; run envboot; run init_${boot}; run main_cpsw0_qsgmii_phyinit; run boot_rprocs; run get_kern_${boot}; run get_fdt_${boot}; run get_overlay_${boot}; run run_kern"
 CONFIG_LOGLEVEL=7
 CONFIG_SPL_MAX_SIZE=0xc0000
+CONFIG_SPL_HAS_BSS_LINKER_SECTION=y
+CONFIG_SPL_BSS_START_ADDR=0x80a00000
 CONFIG_SPL_BSS_MAX_SIZE=0x80000
 CONFIG_SPL_BOARD_INIT=y
 CONFIG_SPL_SYS_MALLOC_SIMPLE=y