binutils: default to 2.21 on sh

uClibc currently doesn't build on sh with 2.21.1, similar to the mips
issue (92496e0).

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

package/binutils/Config.in.host

@@ -2,7 +2,7 @@ comment "Binutils Options"
 
 choice
 	prompt "Binutils Version"
-	default BR2_BINUTILS_VERSION_2_21 if (BR2_mips || BR2_mipsel)
+	default BR2_BINUTILS_VERSION_2_21 if (BR2_mips || BR2_mipsel || BR2_sh)
 	default BR2_BINUTILS_VERSION_2_21_1
 	help
 	  Select the version of binutils you wish to use.