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/at91sam9m10g45ek_mmc_defconfig b/configs/at91sam9m10g45ek_mmc_defconfig
index 0768360..5d27ee1 100644
--- a/configs/at91sam9m10g45ek_mmc_defconfig
+++ b/configs/at91sam9m10g45ek_mmc_defconfig
@@ -11,6 +11,7 @@
 CONFIG_DEBUG_UART_BASE=0xffffee00
 CONFIG_DEBUG_UART_CLOCK=132000000
 CONFIG_DEBUG_UART=y
+CONFIG_SYS_LOAD_ADDR=0x22000000
 CONFIG_SD_BOOT=y
 CONFIG_BOOTDELAY=3
 CONFIG_USE_BOOTARGS=y