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/imx8mm-icore-mx8mm-edimm2.2_defconfig b/configs/imx8mm-icore-mx8mm-edimm2.2_defconfig
index cf385a6..08151f3 100644
--- a/configs/imx8mm-icore-mx8mm-edimm2.2_defconfig
+++ b/configs/imx8mm-icore-mx8mm-edimm2.2_defconfig
@@ -24,6 +24,8 @@
 CONFIG_OF_SYSTEM_SETUP=y
 CONFIG_DEFAULT_FDT_FILE="imx8mm-icore-mx8mm-edimm2.2.dtb"
 CONFIG_SPL_MAX_SIZE=0x25000
+CONFIG_SPL_HAS_BSS_LINKER_SECTION=y
+CONFIG_SPL_BSS_START_ADDR=0x910000
 CONFIG_SPL_BSS_MAX_SIZE=0x2000
 CONFIG_SPL_BOARD_INIT=y
 # CONFIG_SPL_SHARES_INIT_SP_ADDR is not set