fix kernel config for linksys nslu2

target/arm/kernel/linksys-nslu2

@@ -1,5 +1,6 @@
 CONFIG_ARM=y
 CONFIG_ARM_PATCH_PHYS_VIRT=y
 CONFIG_CPU_XSCALE=y
+CONFIG_ARCH_IXP4XX=y
+CONFIG_MACH_NSLU2=y
 CONFIG_ATAGS=y
-CONFIG_ATAGS_PROC=y