u-boot: mark old 2008.10 version as deprecated

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

target/u-boot/Config.in

@@ -30,6 +30,7 @@ config BR2_TARGET_UBOOT_2009_01
 
 config BR2_TARGET_UBOOT_2008_10
 	bool "u-boot-2008.10"
+	depends on BR2_DEPRECATED
 
 config BR2_TARGET_UBOOT_1_3_4
 	bool "u-boot-1.3.4"