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/peach-pit_defconfig b/configs/peach-pit_defconfig
index aaec917..4b87bf2 100644
--- a/configs/peach-pit_defconfig
+++ b/configs/peach-pit_defconfig
@@ -12,6 +12,7 @@
 CONFIG_SPL=y
 CONFIG_IDENT_STRING=" for Peach-Pit"
 CONFIG_DISTRO_DEFAULTS=y
+CONFIG_SYS_LOAD_ADDR=0x23e00000
 CONFIG_FIT=y
 CONFIG_FIT_BEST_MATCH=y
 CONFIG_SILENT_CONSOLE=y