Don't use a string to do the job of a bool

Config.in

@@ -63,8 +63,8 @@ config BR2_WGET
 	default "wget --passive-ftp"
 
 config BR2_TAR_VERBOSITY
-	string
-	default "no"
+	bool
+	default n
 
 source "toolchain/Config.in"
 

Makefile

@@ -35,7 +35,7 @@ ifeq ($(filter $(noconfig_targets),$(MAKECMDGOALS)),)
 -include $(TOPDIR).config
 endif
 
-ifeq ($(strip $(BR2_TAR_VERBOSITY)),"yes")
+ifeq ($(BR2_TAR_VERBOSITY),y)
 TAR_VERBOSITY=v
 else
 TAR_VERBOSITY=