Convert CONFIG_SYS_LOAD_ADDR to Kconfig

Now that we have consistent usage, migrate this symbol to Kconfig.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Rick Chen <rick@andestech.com>
diff --git a/configs/microblaze-generic_defconfig b/configs/microblaze-generic_defconfig
index bd6e10a..8e45cb9 100644
--- a/configs/microblaze-generic_defconfig
+++ b/configs/microblaze-generic_defconfig
@@ -13,6 +13,7 @@
 CONFIG_XILINX_MICROBLAZE0_USE_DIV=1
 CONFIG_XILINX_MICROBLAZE0_USE_HW_MUL=1
 CONFIG_DISTRO_DEFAULTS=y
+CONFIG_SYS_LOAD_ADDR=0x0
 CONFIG_FIT=y
 CONFIG_FIT_VERBOSE=y
 CONFIG_BOOTDELAY=-1