at91sam9rlek_mmc_defconfig: Add CONFIG_ARCH_AT91=y

This flag was missing and thus the board was totally being configured
wrong.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/at91sam9rlek_mmc_defconfig b/configs/at91sam9rlek_mmc_defconfig
index 8704140..41a2821 100644
--- a/configs/at91sam9rlek_mmc_defconfig
+++ b/configs/at91sam9rlek_mmc_defconfig
@@ -1,4 +1,5 @@
 CONFIG_SYS_EXTRA_OPTIONS="AT91SAM9RL,SYS_USE_MMC"
 CONFIG_ARM=y
+CONFIG_ARCH_AT91=y
 CONFIG_TARGET_AT91SAM9RLEK=y
 CONFIG_HUSH_PARSER=y