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/crs305-1g-4s_defconfig b/configs/crs305-1g-4s_defconfig
index 677e248..5fc8058 100644
--- a/configs/crs305-1g-4s_defconfig
+++ b/configs/crs305-1g-4s_defconfig
@@ -10,6 +10,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="armada-xp-crs305-1g-4s"
 CONFIG_BOOTCOUNT_BOOTLIMIT=3
 CONFIG_BUILD_TARGET="u-boot.kwb"
+CONFIG_SYS_LOAD_ADDR=0x800000
 CONFIG_FIT=y
 CONFIG_FIT_VERBOSE=y
 CONFIG_FIT_BEST_MATCH=y