binutils: undeprecate 2.18 for avr32

As discussed on the list. AVR32 is still stuck at 2.18, so don't mark it as
deprecated yet.

toolchain/binutils/Config.in

@@ -20,7 +20,7 @@ choice
 
 	config BR2_BINUTILS_VERSION_2_18
 		depends on !BR2_nios2
-		depends on BR2_DEPRECATED
+		depends on BR2_DEPRECATED || BR2_avr32
 		depends on BR2_EXT_BINUTILS_VERSION_2_18
 		bool "binutils 2.18"