arch: remove the BR2_GCC_TARGET_TUNE option

The BR2_GCC_TARGET_TUNE option is now unused, so we can get rid of it.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

arch/Config.in

@@ -217,9 +217,6 @@ config BR2_ARCH
 config BR2_ENDIAN
 	string
 
-config BR2_GCC_TARGET_TUNE
-	string
-
 config BR2_GCC_TARGET_ARCH
 	string