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/huawei_hg556a_ram_defconfig b/configs/huawei_hg556a_ram_defconfig
index 987ad31..a4f4fbd 100644
--- a/configs/huawei_hg556a_ram_defconfig
+++ b/configs/huawei_hg556a_ram_defconfig
@@ -10,6 +10,7 @@
 # CONFIG_MIPS_BOOT_ENV_LEGACY is not set
 CONFIG_MIPS_BOOT_FDT=y
 # CONFIG_SYS_MALLOC_CLEAR_ON_INIT is not set
+CONFIG_SYS_LOAD_ADDR=0x80100000
 CONFIG_OF_STDOUT_VIA_ALIAS=y
 CONFIG_DISPLAY_CPUINFO=y
 CONFIG_HUSH_PARSER=y