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/qemu-riscv32_spl_defconfig b/configs/qemu-riscv32_spl_defconfig
index 28ac2b3..31f3a69 100644
--- a/configs/qemu-riscv32_spl_defconfig
+++ b/configs/qemu-riscv32_spl_defconfig
@@ -6,6 +6,7 @@
 CONFIG_TARGET_QEMU_VIRT=y
 CONFIG_RISCV_SMODE=y
 CONFIG_DISTRO_DEFAULTS=y
+CONFIG_SYS_LOAD_ADDR=0x80200000
 CONFIG_FIT=y
 CONFIG_SPL_LOAD_FIT_ADDRESS=0x80200000
 CONFIG_DISPLAY_CPUINFO=y