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/am64x_evm_r5_defconfig b/configs/am64x_evm_r5_defconfig
index 669e496..20e1f50 100644
--- a/configs/am64x_evm_r5_defconfig
+++ b/configs/am64x_evm_r5_defconfig
@@ -34,6 +34,8 @@
 CONFIG_SPL_SIZE_LIMIT_SUBTRACT_GD=y
 CONFIG_SPL_SIZE_LIMIT_SUBTRACT_MALLOC=y
 CONFIG_SPL_MAX_SIZE=0x180000
+CONFIG_SPL_HAS_BSS_LINKER_SECTION=y
+CONFIG_SPL_BSS_START_ADDR=0x7019b800
 CONFIG_SPL_BSS_MAX_SIZE=0x4000
 CONFIG_SPL_SYS_REPORT_STACK_F_USAGE=y
 CONFIG_SPL_BOARD_INIT=y